Symposium Organizers
Ruben Perez Universidad Autónoma de Madrid
Suzi Jarvis University College Dublin
Seizo Morita Osaka University
Udo Schwarz Yale University
OO1: Force Spectroscopy
Session Chairs
Monday PM, November 30, 2009
Room 209 (Hynes)
9:30 AM - **OO1.1
Force Spectroscopy: From the Repulsive to the Attractive Regime.
E. Meyer 1 , T. Glatzel 1 , S. Kawai 1 , B. Such 1 , E. Gnecco 1 , S. Koch 1 , P. Steiner 1 , R. Roth 1 , A. Rao 1 , A. Baratoff 1
1 , University of Basel, Basel Switzerland
Show AbstractLow-temperature force microscopes or room-temperature microscopes equipped with atom trapping have a long-term stability, which allows the experimentalists to acquire 3d force spectroscopy above single atoms or molecules. The transition from the so-called non-contact to the repulsive contact is of special interest. Novel phenomena, such as the formation of atomic wires, can be observed in this transition regime. In addition, the microscopes can be operated at multiple frequencies to gain information about the local contact potential difference or the local elasticity. Apart from conservative interactions, which are characteristic for chemical bonds, non-conservative interactions, such as friction or damping, can be investigated with unprecedented lateral resolution. The phenomenon of atomic-scale stick slip is a fundamental process to understand friction. The loading dependence shows a transition from a stick-slip regime of ultralow friction (superlubricity). Multiple slips occur for relatively large loads with small damping.
10:00 AM - OO1.2
Simultaneous Measurement of Force and Tunneling Current with Atomic Force Microscopy.
Masayuki Abe 1 , Daisuke Sawada 1 , Ken-ichi Morita 1 , Yoshiaki Sugimoto 1 , Seizo Morita 1
1 , Osaka University, Suita, Osaka, Japan
Show AbstractWe have performed simultaneous STM and AFM measurements in the dynamic mode using Pt-Ir coated Si cantilevers at room temperature. Frequency shift and time-average tunneling current images were obtained by tip scanning on the Si(111)-(7x7) surface at constant height mode to prevent a crosstalk between these two channels. To compensate the thermal drift of the tip-surface distance, feed-forward technique was applied [1]. Analysis of 25 sets of AFM/STM images using different tips shows that when atomic resolution is obtained simultaneously by both AFM and STM, the tunneling current is much larger than the typical values in conventional STM. We have also performed simultaneous measurements of site-specific force/tunneling spectroscopy. The frequency shift and averaged tunneling current versus tip-surface distance curves were converted into the short-range force and the tunneling current at closest separation between the sample surface and the oscillating tip. We observed the drop in the tunneling current due to the chemical interaction between the tip apex atom and the surface adatom, which was found recently [2], and estimated the value of the chemical bonding force. Furthermore, we performed scanning tunneling spectroscopy on the same site using the same AFM tip. The spectrum is in good agreement with previous STM results. Our results demonstrate that one can quantitatively measure the local density of state and the chemical bonding force above the same atom using the same tip [3].[1]M. Abe, et al., Appl. Phys. Lett. vol.90, p.203103 (2007). [2]P. Jelinek, M. Svec, P. Pou, R. Perez, and V. Chab, Phys. Rev. Lett. vol.101, p.176101 (2008). [3] D. Sawada, Y. Sugimoto, K. Morita, M. Abe, and S. Morita, Appl. Phys. Lett. vol.94, p.173117 (2009).
10:15 AM - OO1.3
Force Fields on a Single Atom Surface Defect by Non-Contact Atomic Force Microscopy.
Andre Schirmeisen 1 , Domenique Weiner 1
1 CeNTech (Center for Nanotechnology), University of Muenster, Muenster Germany
Show AbstractNon-contact atomic force microscopy under ultrahigh vacuum conditions is a powerful tool to investigate the atomic structure of surfaces. The method of 3D force field spectroscopy [1] allows the spatial analysis of vertical and lateral interatomic forces [2], as well as the potential energy landscape with atomic resolution [3]. In this study we focus on the analysis of surface defects on a NaCl(001) crystal by force field spectroscopy. The NaCl sample was cleaved in air and then annealed in ultrahigh vacuum to remove surface contaminations and equilibrate residual charges. Measurements were performed at room temperature with a commercial ultrahigh vacuum atomic force microscope. The spatial force fields with atomic resolution along different crystallographic directions were measured above a surface defect, which appeared as a valley of atomic dimensions in the surface topography. We find that the vertical tip-sample force directly above the defect is more repulsive than above a surface atom. From the force fields we calculate the atomic scale potential energy landscape, which is compared to model calculations. This model is based on electrostatic interactions of hard spheres and assumes an ion terminated tip apex. According to this model our experimental potential energy fields agree best with a situation where a single ion is missing in the surface. This raises questions about the unexpected stability of single charge defects in an ionic surface. [1] Holscher, Langkat, Schwarz, Wiesendanger, Appl. Phys. Lett. 81, 4428 (2002)[2] Ruschmeier, Schirmeisen, Hoffmann, Phys. Rev. Lett 101, 156102 (2008)[3] Schirmeisen, Weiner, Fuchs, Phys. Rev. Lett. 97, 136101 (2006)
10:30 AM - OO1.4
Quantification of Chemical Forces with Picometer Resolution using Three-dimensional Atomic Force Microscopy.
Udo Schwarz 1 2 , Mehmet Baykara 1 2 , Todd Schwendemann 1 2 , Boris Albers 1 2 , Nicolas Pilet 1 2 , Eric Altman 2 3
1 Mechanical Engineering, Yale University, New Haven, Connecticut, United States, 2 Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut, United States, 3 Chemical Engineering, Yale University, New Haven, Connecticut, United States
Show AbstractSite-specific surface chemical interactions govern numerous scientific and technological fields including catalysis, thin film growth, and tribology. Full control over design processes in these fields requires quantitative, site-specific elaboration of the surface force field. Until now, such information has only been theoretically accessible. In this talk, we present an atomic force microscopy-based approach to experimentally obtain this data and illustrate its application by imaging the three-dimensional surface force field of graphite.Graphite has been chosen due to its importance as a solid lubricant as well as model system for multilayer graphene. We show force maps with picometer and piconewton resolution that allow a detailed characterization of the distance-dependent surface-probe interactions vertically as well as laterally. Within these maps, the positions of all atoms are identified, and differences between atoms at inequivalent sites are quantified. The results suggest that the origin of graphite’s excellent lubrication properties may lay in a remarkable localization of the lateral forces. Future applications of this method in areas such as chemical imaging and surface catalysis are envisioned.
10:45 AM - OO1.5
Interpretation of the Chemical Forces Measured by Force Spectroscopy on Semiconductor and Carbon Based Materials Surfaces.
Pablo Pou 1 , Ruben Perez 1
1 Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, Madrid Spain
Show AbstractThe NCAFM has demonstrated its outstanding abilities to image, manipulate and chemically identify atoms in all kinds of surfaces [1-3]. Nowadays, it is possible to perform high precision on site force spectroscopy experiments even at room temperature which has opened the door to measure 3D force mappings [4-6]. In addition to the experimental information, a theoretical interpretation of the experimental findings is required in order to gain detailed atomic insight and deeply understand the physics behind the measurements. Traditionally, atomistic simulations, mainly based on DFT, have been the first choice to perform theoretical studies [1,3], however the reduced size of simulated systems does not allow a correct description of the elasticity of the system. We propose a method to improve the study of the force curves (force vs. tip-sample distance curves). This method combines the chemical interaction between the outermost apex atoms with the closer surfaces atoms with the elastic response of both tip and sample. The analysis the force curves from this point of view allows understanding the physical properties behind the chemical identification method based on the force maxima [3]. We show the accuracy and the validity of this method using DFT simulations on semiconductor surfaces. Moreover, we extend it to the analysis of the experimental data on the Sn/Si(111) surface.Besides the semiconductor systems, where the interaction is dominated by the covalent bond between the outermost tip atom and a surface atom, we also explore carbon nanotubes where dispersion forces are expected to have an important contribution to the tip-sample interaction. Therefore, we have studied this system using a standard DFT calculation adding the dispersion forces based on the semiempirical Grimme approach [7]. We have carried out calculations of the interaction of a large set of AFM tips with different low-dimension carbon materials. We have considered several possible tip terminations: reactive clean Si tip apexes, non-reactive apexes, oxygen contaminated Si apexes and metallic tips. Our results provide insight into the origin of the atomic contrast observed in recent experiments on both SWNT and peapods constituted by endo-fullerenes inserted in a SWNT [8,9].[1] R. Garcia et al., Surf. Sci. Rep. 47, 197 (2002), F. J. Giessibl, Rev. Mod. Phys. 75, 949 (2003).[2] Y. Sugimoto et al., Nature Materials 4, 156 (2005).[3] Y. Sugimoto et al., Nature (2007).[4] H. Hölscher et al., Appl. Phys. Lett. 81, 4428 (2002).[5] Y. Sugimoto et al. Phys. Rev. B 77, 195424 (2008).[6] B. J. Albers et al. Nature Nanotech. 4, 57 (2009). [7] S. Grimme, J Comput Chem, 27, 1787 (2006). [8] M. Ashino et al. Nature Nanotech. 3, 337 (2008),M. Ashino et al. PRL 93, 136101 (2004); M. Ashino et al. Nanotechnology 16, S134-S137 (2005).
11:30 AM - **OO1.6
Applications of Microsecond Force Spectroscopy.
Ozgur Sahin 1
1 Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts, United States
Show AbstractRecently developed torsional harmonic cantilevers allow high speed force spectroscopic measurements with nanometer scale spatial resolution and microsecond scale temporal resolution. Detailed information hidden in the force spectroscopic data can be analyzed by computer programs to extract material properties like elastic modulus, adhesion force, and if chemical interactions are present, the force required to rupture chemical bonds. Due to the high speed of operation, the resulting material properties can be mapped across surfaces while the cantilever is scanning in the tapping mode. Accessing broad range of material properties quantitatively and with high spatial resolution enables new platforms for genetic analysis, single molecule studies, compositional mapping of biological membranes, and material characterization. We will present recent developments in these areas.
12:00 PM - OO1.7
Advances in Dynamic Mode Scanning Force Spectroscopy in Ambient Conditions.
Jaime Colchero 1 , Ines Nieto Carvajal 1 , Jose Abad 1 , Elisa Palacios-Lidon 1
1 of Physics, Universidad de Murcia, Murcia Spain
Show AbstractQuantitative characterization of tip-sample interaction in a Scanning Probe Microscopy setup is fundamental for optimum image acquisition as well as data interpretation. In this work we discuss how Dynamic Scanning Scanning Force Microscopy (DSFM) techniques can be utilized to acquire precise spectroscopy data in order to characterize tip-sample interaction in ambient conditions. The spectroscopic technique presented is based on the simultaneous measurement of cantilever deflection, oscillation amplitude and frequency shift. Measurement of two dimensional data sets - “interaction images”- allow a precise characterization of tip-sample forces. Two methods will be described: data can be acquired either as a function of tip-sample voltage and tip-sample distance [1] allowing to separate the Van der Waals force from the electrostatic force, or , alternately, data can be acquired simply as a function of time, in order to determine the dynamics of the tip-sample system (resonance frequency, oscillation amplitude and quality factor) from the thermal fluctuations of the cantilever motion [2]. In this latter case, the low oscillation amplitude of the cantilever simplifies the interpretation of data is considerably simplified, since nonlinearities are avoided.Using appropriate data-processing we show that from the acquired data sets, the Van der Waals interaction, the capacitance as well as the contact potential can be determined as a function of tip-sample distance. The measurement of resonance frequency shift yields very high signal to noise ratio and the absolute calibration of the measured quantities; while the acquisition of cantilever deflection allows the determination of tip-sample distance. We show that the high resolution of the data acquired allows to check the validity of typical models for the tip-sample behavior (van der Waals forces, electrostatic interaction) and discuss the deviations that are observed. We believe that our results are important not only to establish the detection limits of DSFM spectroscopy, but also to explore the fundamental mechanism for tip-sample interaction and dissipation in DSFM experiments performed in ambient conditions. In addition, precise determination of tip-sample interaction is an important tool for the correct interpretation of DSFM images [3].[1] E. Palacios and J. ColcheroA technique for the separation of electrostatic and Van der Waals interaction in Scanning Force Microscopy”, Nanotechnology 17 (21), 5491 – 5500 (2006).[2] J. Abad and Colchero, to be published[3] E. Palacios-Lidón, B. Pérez-García, J. Colchero“Enhancing Dynamic Scanning Force Microscopy in air: As close as possible”Nanotechnology 20 , 085707-1– 085707-7 (2009).
12:15 PM - OO1.8
Dynamic Force Spectroscopy of Single Chain-like Molecules using the Frequency Modulation Technique with Constant-excitation.
Hendrik Hoelscher 1 , Daniel Ebeling 2 , Filipp Oesterhelt 3
1 Institute for Microstructure Technology, Forschungszentrum Karlsruhe, Karlsruhe Germany, 2 Center for Nanotechnology, University of Muenster, Muenster Germany, 3 Institut fuer Physikalische Chemie II, University of Duesseldorf, Duesseldorf Germany
Show AbstractTo measure forces acting on a chain-like molecule in liquid, we introduce a dynamic approach based on the frequency-modulation technique with constant-excitation. In difference to the classical approach where the force is recorded as a conventional force vs. distance curve in a static measurement, we are able to detect simultaneously the conservative force as well as the energy dissipation during the elongation of a chain-like molecule. We apply this technique to dextran monomers and demonstrate the agreement of the experimental force curves with a "single-click" model.
12:30 PM - OO1.9
Energy Dissipation Measurements in Frequency Modulated Scanning Probe Microscopy.
Roger Proksch 1
1 Roger Proksch, Asylum Research, Santa Barbara, California, United States
Show AbstractNon-contact atomic force microscopy based around frequency modulation has been shown to be a versatile tool for high resolution, high sensitivity measurements of structure and forces on the nanometer, atomic, and even sub-atomic level in vacuum, ambient and liquid conditions. In the last several years, measuring dissipation has attracted increasing interest as it provides information on energy losses and hysteretic phenomena associated with magnetic, electrical, and structural transformations at the tip-surface junction. Here, we demonstrate that in traditional heterodyne detection schemes the amplitude and phase dispersion in the cantilever drive can change the quantitative and even the qualitative dissipation. In magnetic dissipation imaging of an yttrium-iron garnet (YIG) sample, the amplitude dispersion as small as one part in 100,000 per Hz is readily observable. At the same time, the AFMs used in this study commonly exhibited one hundred times greater dispersion (one part in 1,000). We demonstrate a calibration method that allows the transfer function dispersion to be successfully accounted for and discuss prospects for quantitative energy dissipation probing on the nanoscale.
12:45 PM - OO1.10
Towards Ultimate Resolution of Atomic Force Microscopy.
Nikolaj Moll 1 , Leo Gross 1 , Fabian Mohn 1 , Peter Liljeroth 1 2 , Alessandro Curioni 1 , Gerhard Meyer 1
1 Zurich Research Laboratory, IBM Research, Rüschlikon Switzerland, 2 Debye Institute for Nanomaterials Science, Utrecht University, Utrecht Netherlands
Show AbstractTo increase the resolution of surface microscopy is one of the most significant goals of surface science. The resolution of atomic force microscopy (AFM) is critically defined and scaled by the radius of the AFM tip. Ultimate resolution can be achieved by functionalizing the tip with a molecule if the interaction of that tip molecule will contribute significantly to the measured force. However, for such tips the contrast will crucially depend on the chemical nature of the terminating tip molecule. Employing ab initio density functional theory (DFT) the influence of the tip termination is studied. The calculations show that Pauli repulsion is the source of the high resolution, whereas van-der-Waals and electrostatic forces only add a diffuse attractive background. This enhancement of the resolution is also observed experimentally and compares very well with theoretical findings.
OO2: Electronic Properties
Session Chairs
Monday PM, November 30, 2009
Room 209 (Hynes)
2:30 PM - **OO2.1
Electron Energy Level Spectroscopy in InAs Quantum Dots by AFM.
Peter Grutter 1 , Lynda Cockins 1
1 Physics, McGill University, Montreal, Quebec, Canada
Show AbstractThe ability of quantum dots to confine single charges at discrete energy levels makes them a promising platform for quantum computation where the intrinsic properties of single electrons, such as spin, act as the conventional 1 and 0 bit in a classical computer. In order to control initialization and to scale up the number of bits, an understanding of both the energy levels of single quantum dots and the variation between dots is needed. Self-assembled quantum dots are of considerable interest in this field because their size, shape, and material can be controlled. These properties is important as they influence the confinement potential, thereby controlling the energy levels of the dot. However, the method of growth does not allow for positioning of the quantum dots which end up randomly distributed over the sample surface. This makes it difficult for lithography techniques to access the quantum dots to perform either charge transport or charge sensing measurements so that the dot properties can be measured.An atomic force microscope can be used to spatially access the dots, and by applying a voltage between cantilever tip and back-electrode, the energy levels of individual dots can be probed. At low temperatures the dots are in the Coulomb blockade regime and individual electrons can be controllably added by applying a sufficient bias voltage to overcome this electrostatic repulsive energy. The oscillating cantilever in these experiments is responsible for both loading/emptying the dots through electrical gating and also detecting tunneling events through a change in resonant frequency and/or the amount of energy required to maintain a constant oscillation amplitude. Electrical leads are not required in this experiment which not only leaves the surface electrostatically intact but also gives us the freedom to investigate any dot on the surface. Using an AFM we demonstrate the ability to probe the electron levels in few electron self-assembled InAs quantum dots. The charging energy, level spacing, and shell structure of single dots are extracted experimentally. In this contribution, we present the mechanism of the dissipative electrostatic interaction due to the tunneling single-electrons in detail. In essence, this dissipative interaction arises from the delayed response of a single tunneling electron to the oscillating chemical potential induced by the oscillating tip. The delay is due to the finite tunneling rate which is determined by the tunnel barrier. We developed a theoretical model for this dissipation process and obtained a very good agreement between the theoretical dissipation versus Vbias curve and the experimental ones. Multi-dot complexes are also investigated and pairs of dots which are either capacitively or tunnel coupled are observed. Finally, we show how by increasing the oscillation amplitude of the cantilever we can probe the excited states of the dot similar to excited state spectroscopy.
3:00 PM - OO2.2
Nanoelectrical Probing with Multiprobe SPM Systems Compatible with Scanning Electron Microscopes.
Aaron Lewis 1 , Andrey Ignatov 2 , Hesham Taha 2 , Oleg Zhinoviev 2 , Anatoly Komissar 2 , Sasha Krol 2 , David Lewis 2
1 , Hebrew University of Jerusalem, Jerusalem, 0, Israel, 2 , Nanonics Imaging Ltd., Jerusalem, 0, Israel
Show AbstractA scanning electron microscope compatible platform that permits multiprobe atomic force microscopy based nanoelectrical characterization will be described. To achieve such multiple parameter nanocharacterization with scanning electron microscope compatibility involves a number of innovations both in instrument and probe design. This presentation will focus on how these advances were achieved and the results obtained with such instrumentation on electrical nano-characterization and electrical nano-manipulation. The advances include: 1. Specialized scanners; 2. An ultrasensitive feedback mechanism based on tuning forks with no optical feedback interference that can induce carriers in semiconductor devices; and 3. Unique probes compatible with multiprobe geometries in which the probe tips can be brought into physical contact with one another. Experiments will be described with such systems that will include multiprobe electrical measurements with metal and glass coated coaxial nanowires of platinum. This combination of scanning electron microscopes integrated with multiprobe instrumentation allows for important applications not available today in the field of semiconductor processing technology.
3:15 PM - OO2.3
Mapping of Local Conductivity Variations by Scanning Conductive Torsion Mode Microscopy.
Stefan Weber 1 , Niko Haberkorn 2 , Maria Retschke 1 , Hans-Juergen Butt 1 , Patrick Theato 2 , Ruediger Berger 1
1 , Max Planck Institute for Polymer Research, Mainz Germany, 2 Institute of Organic Chemistry, Johannes Gutenberg University, Mainz Germany
Show AbstractWith the ongoing miniaturization of electronic structures and the upcoming of flexible electronic materials there is a strong demand for non-invasive characterization methods on nanometer length scales. Therefore, scanning force microscopy (SFM) techniques, in particular those operated in a non-contact mode, become increasingly important for soft and flexible materials [1].One of the most prominent methods to analyze electronic properties with SFM is conductive scanning force microscopy (C-SFM). This mode uses a metal coated tip which is scanned in contact mode over a biased sample surface. In parallel to the topography, the electrical current flow between sample and the SFM-tip is recorded. Thus, topographical features can be correlated with the local electrical performance and defects can be identified [2]. However, the operation of C-SFM in contact mode imposes several drawbacks: Soft surfaces may be permanently damaged by (i) tip induced forces, (ii) high electric fields and (iii) high current densities close to the SFM-tip. Hence, a non-contact operation for C-SFM would be very beneficial in order to control and reduce these issues. We have developed such a novel non-contact operation mode to investigate local conductivity variations. This mode is based on torsion mode topography imaging. Here, the SFM-tip vibrates laterally with respect to the sample surface and thus remains in close proximity to the surface. By applying an electrical potential between the cantilever and the sample a measurable electrical current flows. By scanning the tip, local variations in the conductivity can be studied. We will demonstrate the performance of our new scanning conductive torsion mode microscope (SCTMM) with a comparative study with conventional C-SFM. In a first step, we investigated a hard nanostructured reference sample. The SCTMM gave comparable results to the standard C-SFM demonstrating that the different operation mode did not generate additional effects or artefacts.The application of SCTMM to the organic electronic hole injection layer PEDOT:PSS will be discussed. We found that with the novel mode tip induced irreversible changes in the PEDOT:PSS surface, often reported for conventional C-SFM on this system [3], can be controlled and avoided much better.Moreover, SCTMM allowed the investigation of delicate samples which were not accessible by standard C-SFM. We will present the results of samples covered with free standing nanometer sized conductive polymer rods fabricated by a templating method [4]. The application of SCTMM allowed us to image the flexible surface at high resolution while measuring the conductivity of individual rods.[1] Berger, R., et al., Electrical Modes in Scanning Probe Microscopy, Macromol. Rapid Comm., 2009, 30.[2] Memesa, M. et al., Energy Environ. Sci., 2009, doi: 10.1039/b902754h.[3] Dang, X.-D. et al., Applied Physics Letters, AIP, 2008, 93, 241911.[4] Haberkorn, N. et al., ACS Nano, 2009, 3, 1415-1422.
3:30 PM - OO2.4
Frequency Modulation, KPM and Electrostatic Force Microscopy in Ambient Air.
Adriana Gil 1 , Pablo Ares 1 , Ignacio Horcas 1 , Rafael Fernandez 1 , Belen Rojo 1
1 , Nanotec Electronica S.L., Tres Cantos, Madrid Spain
Show AbstractElectrostatic Force Microscopy (EFM) and Kelvin Probe Microscopy (KPM) have been applied to study the electric properties of a variety of samples at the nanometric scale. The result of these measurement modes gives complementary information about the electric properties of the sample to that obtained from the contact measurements. Since the EFM and KPM avoid the mechanical contact between the tip and the molecule under study, the result is not affected by deformation of the sample. Moreover, the effect of the electrical contact between the molecule and the electrodes, which is usually a problem in transport measurements at the nanometric scale, is minimised. Therefore the EFM and KPM are considered as non-intrusive techniques to analyse the electrostatic properties of nanowires.The advantages of the combination of EFM and KPM with Frequency Modulation Dynamic Mode AFM, which is routinely applied in Ultra High Vacuum, can also be exploited in ambient air and will be discussed in this work together with spectroscopic measurements for electrostatic characterization of samples.
4:15 PM - OO2.5
3D Imaging & Spectroscopy of Electron Trap States in high-K Dielectric Films by Force Detected Tunneling.
John Johnson 1 , Dustin Winslow 1 , Clayton Williams 1
1 Department of Physics, University of Utah, Salt Lake City, Utah, United States
Show AbstractAtomic scale imaging of electron trap states in completely non-conducting dielectric films has previously been demonstrated with Dynamic Tunneling Force Microscopy (DTFM)[1]. In that work, the DTFM signal was observed to depend upon trap state depth. Here, a methodology is described to independently determine the energy and physical depth of a particular state through a series of Single Electron Tunneling Force Spectroscopy (SETFS) measurements. The method provides, for the first time, a means to obtain true three-dimensional images of electron trap states, simultaneously with a determination of their energy in the dielectric band gap. The approach is useful in the characterization of films used as gate materials and in flash memory applications. The methodology will be described and imaging/energy results will be shown on high-K dielectric films. [1] J.P.Johnson, N. Zheng and C.C. Williams, “Atomic scale imaging and spectroscopy of individual electron trap states using force detected dynamic tunneling,” Nanotechnology 20, 055701 (2009).
4:30 PM - OO2.6
Domain Switching Dynamics in the Ferroelectric Polymer Films Studied at the Nanoscale.
Pankaj Sharma 1 , Timothy Reece 1 , Stephen Ducharme 1 , Alexei Gruverman 1
1 Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska, United States
Show AbstractCopolymer polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) has been in talk for its potential applications in microelectromechanical systems and mass data storage devices. However, still a lot of work needs to be done to understand the static and dynamic behavior of PVDF-TrFE at the nanoscale. In this study, Piezoresponse Force Microscopy (PFM) has been used to investigate the morphology effect on polarization distribution and switching properties of ultrathin films of PVDF-TrFE (80:20). The films were deposited on highly doped Si substrate using the Langmuir-Blodgett technique. Films morphology and crystallinity have been controlled by depositing a varying number of molecular monolayers (ML) and subjecting films to annealing. The PVDF-TrFE films of 1 ML and 3 ML thickness exhibited isolated mesas approximately 200-400 nm in lateral size. The PFM images show that the mesas are in generally in a polydomain state which can be modified by applying a bias to the PFM tip. In this paper, we report the switching studies of the PVDF-TrFE nanomesas as a function of bias magnitude and duration. The results show that the domain growth is strongly influenced by the defects, grain boundaries and the pinning centers. It is found that the domain growth is of the fractal type with the fractal dimension of ~ 1.4. A 2D map of the local switching parameters has been obtained by detecting local PFM hysteresis loops to locate the pinning centers and the defects.
OO3: Magnetic Properties
Session Chairs
Monday PM, November 30, 2009
Room 209 (Hynes)
4:45 PM - **OO3.1
Perspectives of Magnetic Exchange Force Microscopy.
Roland Wiesendanger 1
1 Institute of Applied Physics, University of Hamburg, Hamburg Germany
Show AbstractA fundamental understanding of magnetic and spin-dependent phenomena requires the determination of spin structures and spin excitations down to the atomic scale. The direct visualization of atomic-scale spin structures [1-4] has first been accomplished for magnetic metals by combining the atomic resolution capability of Scanning Tunnelling Microscopy (STM) with spin sensitivity, based on vacuum tunnelling of spin-polarized electrons [5]. The resulting technique, Spin-Polarized Scanning Tunnelling Microscopy (SP-STM), nowadays provides unprecedented insight into collinear and non-collinear spin structures at surfaces of magnetic nanostructures and has already led to the discovery of new types of magnetic order at the nanoscale [6]. More recently, the detection of spin-dependent exchange and correlation forces has allowed a first direct real-space observation of spin structures at surfaces of antiferromagnetic insulators [7]. This new type of scanning probe microscopy, called Magnetic Exchange Force Microscopy (MExFM), provides a powerful new tool to investigate different types of spin-spin interactions based on direct-, super-, or RKKY-type exchange down to the atomic level, in contrast to MFM where the magnetic dipole forces are probed with a ferromagnetic probe tip at a typical tip-to-surface distance of 10-20 nm [8,9]. By combining MExFM with high-precision measurements of damping forces [10] localized or confined spin excitations in magnetic systems of reduced dimensions now become experimentally accessible. MExFM combines the possibilities of NC-AFM and atomic-scale spin resolution by making use of an atomically sharp probe tip with a very well defined spin state at its apex. Based on the knowledge gained during the development of SP-STM in preparing such tips we have succeeded in resolving the surface spin structure of the antiferromagnetic insulator NiO(001) [7]. More recently, MExFM has been applied to the antiferromagnetically ordered ground state of a single atomic layer of Fe on a W(001) substrate [11] for which a direct comparison with SP-STM results [3,4] could be made. Significant differences in the distance-dependence of the MExFM contrast have been observed between the NiO(001) and Fe/W(001) surfaces.References:[1]R. Wiesendanger et al., Science 255, 583 (1992); R. Wiesendanger et al., Europhys.Lett. 19, 141 (1992). [2]S. Heinze et al., Science 288, 1805 (2000). [3]A. Kubetzka et al., Phys.Rev.Lett. 94, 087204 (2005). [4]M. Bode et al., Nature Mater. 5, 477 (2006). [5]R. Wiesendanger et al., Phys.Rev.Lett. 65, 247 (1990). [6]K. von Bergmann et al., Phys.Rev.Lett. 96, 167203 (2006). [7]U. Kaiser, A. Schwarz, and R. Wiesendanger, Nature 446, 522 (2007). [8] Y. Martin and K. Wickramsinghe, Appl.Phys.Lett. 50, 1455 (1987); J. J. Saenz et al., J.Appl.Phys. 62, 4293 (1987). [9]A. Schwarz et al., Phys.Rev.Lett. 92, 077206 (2004). [10]M. Ashino et al., Phys.Rev.Lett. 102, 195503 (2009). [11]R. Schmidt et al., Nano Lett. 9, 200 (2009).
5:15 PM - OO3.2
Magnetic Domain Structure in Magnetic Writing Head Observed by Scanning Lorentz Force Microscopy.
Seiichi Suzuki 1 , Yu Yahagi 1 , Suguru Tanaka 1 , Katsuaki Yanagiuchi 2 , Yutaka Majima 1
1 Material and Structures Laboratory, Tokyo Institute of Technology, Tokyo Japan, 2 , TDK Corporation, Nagano Japan
Show Abstract“Pole erasure” problem is one of the main issues towards ultra-high-density (UHD) magnetic recording, in which the recorded data can be erased during the non-write operation due to the remanent magnetic field of the write pole itself [1]. Therefore it is essential to measure the magnetic domain structure of the writing pole and also the distribution of the stray field [2]. We have proposed scanning Lorentz force microscopy (SLFM) as a novel technique to observe magnetic domain and topography simultaneously with the spatial resolution of 40 nm by means of scanning probe method [3, 4]. SLFM is based on a contact mode atomic force microscopy (AFM) and a conductive cantilever is employed instead of magnetic –coated tip in this technique. The main advantage of SLFM is that it is possible to observe magnetic domain behaviors when an external magnetic field is applied because the SLFM cantilever does not need to contain magnetic materials. An ac voltage is applied to the conductive cantilever, which is in contact with the sample, to make current flow through the tip. The tip current and a lateral stray magnetic flux density from a magnetic sample generate the Lorentz force which twists the cantilever in accordance with Fleming’s left hand rule at a resonant frequency. This Lorentz force causes the cantilever to undergo a lateral torsion since the direction of the Lorentz force is in the plain of the cantilever. Meanwhile, the surface topography corresponds to the vertical deflection of the cantilever.Here we demonstrate SLFM images of the cut-plane sample of the HDD write pole along with its topography under external magnetic field by means of SLFM. The magnetic domain structure and stray magnetic field from the tip was observed in SLFM images.[1] K. Hirata, A. Yamaguchi, M. Ohtsuki, T. Roppongi, and K. Noguchi, J. Appl. Phys., 99, 08E711 (2006).[2] J. J. Kim, K. Hirata, Y. Ishiba, O. Shindo, M. Takahashi, and A. Tonomura, Appl. Phys. Lett., 92, 162501 (2008).[3] A. Okuda, J. Ichihara, and Y. Majima, Appl. Phys. Lett., 81, 2872 (2002).[4] S. Suzuki, Y. Azuma, and Y. Majima, Appl. Phys. Lett., 90, 053110 (2007).
5:30 PM - OO3.3
Sub-10nm Resolution in Magnetic Force Microscopy(MFM) at Ambient Conditions.
Ozgur Karci 1 2 , Hilal Atalan 1 , Munir Dede 1 , Umit Celik 3 , Ahmet Oral 4
1 , NanoMagnetics Instruments Ltd., Oxford United Kingdom, 2 Department of Nanoscience & Nanomedicine, Hacettepe University, Ankara Turkey, 3 Department of Material Science, Istanbul Technical University, Istanbul Turkey, 4 Faculty of Engineering & Natural Sciences, Sabanci University, Istanbul Turkey
Show AbstractWe describe designs of high resolution Magnetic Force Microscopes, which can achieve better than 10nm resolution in magnetic imaging even in ambient conditions. We developed two different MFMs, which can both achieve better than 10nm lateral resolution, using commercially available, off the shelf, magnetically coated cantilevers. Both MFMs have been optimized to have low noise. One of the instruments is designed for low temperature use, 300mK-300K using low noise fiber optic interferometer & alignment free cantilevers. The other MFM is designed to operate in ambient conditions and employ a beam deflection pickup with optimized noise performance. Both MFMs can also be operated in bimodal operation, using first and second resonance of the magnetically coated cantilever for topography and magnetic contrast.
Symposium Organizers
Ruben Perez Universidad Autónoma de Madrid
Suzi Jarvis University College Dublin
Seizo Morita Osaka University
Udo Schwarz Yale University
OO4: Operation in Liquids
Session Chairs
Tuesday AM, December 01, 2009
Room 209 (Hynes)
9:30 AM - **OO4.1
Instrumentation and Applications of Liquid-Environment Frequency Modulation Atomic Force Microscopy.
Takeshi Fukuma 1
1 Frontier Science Organization, Kanazawa University, Kanazawa Japan
Show AbstractFrequency modulation atomic force microscopy (FM-AFM) has been widely used for imaging atomic- and molecular-scale structures of various surfaces including insulators. While the method has mainly been used in ultrahigh vacuum environments, recent advancement in its instrumentation[1] has made it possible to operate FM-AFM in liquid with true atomic resolution[2] using a stiff cantilever, small oscillation amplitude and a low noise cantilever deflection sensor.The two major application areas of liquid-environment AFM include biology and electrochemistry. To date, FM-AFM has been mainly used in the former area. For example, molecular-resolution imaging of model biological membranes[3], proteins[4], macromolecular assemblies[5] have been demonstrated. In addition, FM-AFM has also enabled to visualize spatial distribution of the interactions between biological molecules and surrounding physiological environment (i.e., water and ions). So far, visualization of hydration layers[6] and mobile ions[7] on a model biological membrane has been demonstrated. Furthermore, three-dimensional distribution of hydration has been directly imaged with atomic-scale resolution.In contrast to the increasing reports on FM-AFM applications in biology, its use in electrochemistry has not been reported. Although electrochemical scanning tunneling microscopy (EC-STM) has been successfully used in atomic-scale studies in this area, there have been growing demands for investigating non-conductive molecules fixed onto a solid substrate. For example, biosensors, biofuel cells and dye-sensitized solar cells utilize functional biological or organic molecules attached onto a solid substrate. The high-resolution liquid-environment FM-AFM combined with a control function of electrochemical potential of AFM tip should an ideal tool for studying electrochemical processes in such devices at molecular-scale resolution.In this paper, recent development of our liquid-environment FM-AFM and its applications to subnanometer-scale studies in liquid are presented.[1] T. Fukuma et al., Rev. Sci. Instrum. 76 (2005) 053704.[2] T. Fukuma et al., Appl. Phys. Lett. 87 (2005) 034101.[3] M. J. Higgins et al. Biophys. J. 91 (2006) 2532.[4] B. W. Hoogenboom et al., Appl. Phys. Lett. 88 (2006) 193109.[5] T. Fukuma et al., Nanotechnol. 19 (2008) 384010.[6] T. Fukuma et al., Biophys J. 92 (2007) 3603.[7] T. Fukuma et al., Phys. Rev. Lett. 98 (2007) 106101.
10:00 AM - OO4.2
Atomic Force Microscopy of Individual Water Molecules at Room Temperature.
Hideki Kawakatsu 1 , Shuhei Nishida 1 , Dai Kobayashi 1
1 Instutute of Industrial Science, University of Tokyo, Tokyo, Tokyo, Japan
Show AbstractHeterodyne laser doppler interferometry has enabled atomic force microscopy in the megahertz regime with 10 pm order vibrations in liquid and vacuum. Both lateral and torsional vibrations could be excited and measured with very low crosstalk. In vacuum, silicon (111) 7x7 was imaged with amplitude of drive of less than 30pm. Mechanical single atom manipulation of silicon, as well as atomic resolution lateral force microscopy were successfully implemented at room temperature. The results showed extremely good matching with calculations showing the potential of the method to map force fields near the surface three dimensionally. Giant corrugation of graphite was observed, also with a 100 pm amplitude, which was ascribed to local deformation of the graphene layers. In liquid, incorporation of photothermal exictation of the AFM cantilever has enabled imaging of individual water molecules ordered on the surface of mica at room temperature. The structured water molecules were seen to fluctuate in the order of minutes. A single water molecule was seen to reside in registry with the lower completed later in the order of seconds. The talk will address the novel instrumentation and the model of what we are seeing in water.
10:15 AM - OO4.3
Real-time in situ AFM of the Electrochemical Growth of Mesocrystals.
Sara Dale 1 , Simon Bending 1 , Laurie Peter 2
1 Department of Physics, University of Bath, Bath United Kingdom, 2 Department of Chemistry, University of Bath, Bath United Kingdom
Show AbstractIn situ AFM has been used to monitor the electrochemical growth of a range of different mesoscopic crystals in real time. The aim of these studies is to establish and optimise the electrochemical conditions giving rise to facetted crystal habits, which in turn controls their physical properties (e.g. magnetisation). Here we report the coupling of electrochemistry with AFM in solution to study bismuth deposition and growth. The 3D growth of such crystals was under diffusion control and the deposition rate slow enough to monitor the growth in real time. A two-step electrochemical potential was applied to the working electrode where the first was a high potential to nucleate the bismuth on the surface and the second a long low potential for imaging the crystal growth habit. Slow growth rates were also ensured by using large cantilever tips which hindered the transport of bismuth to the surface by diffusion. We have performed a detailed analysis our AFM images to establish time-dependent volume growth rates of individual microcrystals, and map local height variations by subtracting sequential AFM images. In this way we are able to build up a microscopic picture of the growth mechanism for these rhombohedral structures which follows a complex step-flow growth pattern with steps originating from topographic peaks on the crystals.
10:30 AM - **OO4.4
Quantitative Dynamic AFM Force Measurements in Fluid.
John Sader 1
1 Department of Mathematics and Statistics, University of Melbourne, Melbourne, Victoria, Australia
Show AbstractDue to its relevance to biological and colloidal systems and sensing applications, there is growing interest in the application of dynamic AFM methods to the quantitative determination of forces in fluid systems. While operation in fluids presents no conceptual difficulty, additional complexity arises since the dynamic properties of microcantilevers are strongly dependent on the surrounding fluid.In this talk, I shall present results of a detailed theoretical investigation of the dynamic properties of microcantilevers in fluid environments and the application of these results to dynamic force measurements. This will include a discussion of the behavior of microcantilevers in fluid in proximity to a surface as typically required in dynamic force spectroscopy studies and MEMS applications, their behavior far from a surface as is often required in sensing applications, the effect of higher order modes on the dynamic response and an overview of dynamic cantilever calibration methods. This has significant implications to the quantitative measurement of forces in fluid using dynamic methods such as Frequency Modulation AFM, which will be discussed. I will also present recent work dealing with a new class of microfluidic cantilever resonator that embeds the fluid in its interior. Applications arising from this fundamental work shall be discussed.
OO5: Imaging Biological Materials
Session Chairs
Tuesday PM, December 01, 2009
Room 209 (Hynes)
11:30 AM - **OO5.1
Nanoscale Electromechanics: The New Dimension of Scanning Probing Microscopy.
Sergei Kalinin 1 , Stephen Jesse 1 , Senli Guo 1 , Maxim Nikiforov 1
1 , ORNL, Oak Ridge, Tennessee, United States
Show AbstractHarnessing electrically induced and controlled mechanical motion on molecular level will pave the way to molecular electromechanical machines – a complement to molecular electronics to allow not only to “think” but also to “act” on the nanoscale. Giving the ubiquity of electromechanical coupling in inorganic, molecular, and biological systems, it also provides a powerful approach for studies of local structure and functionality on the nanometer scale. Achieving this goal requires the capability for probing electromechanical conversion mechanisms and associated energy dissipation on nanometer and molecular levels, necessary to select suitable systems from the variety of existing molecular and biological electromotors, and learn their operation and control mechanisms. Here, I will present the recent advances in SPM methods for probing nanoscale electromechanics in inorganic and biological systems. The use of band excitation method allows efficient use of resonance enhancement in electromechanical excitation. The analysis of resulting multidimensional data sets requires multivariate statistical methods and neural network based analysis. Several recent examples including (a) bacterial recognition based on broadband electromechanical response, (b) probing ferroelectricity in biosystems in ambient environment and (c) measuring piezoelectricity of biological systems such as amyloid fibrils in liquid will be illustrated.The research is supported by the Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC for the Office of Basic Energy Sciences, US Department of Energy.
12:00 PM - OO5.2
Scanning Probe Recognition Microscopy (SPRM) - A New Tool for Quantitative Mapping of the Nanoscale Properties of Biomaterials.
V. Ayres 1 , V. Tiryaki 1 , A. Khan 2 , R. Delgado-Rivera 3 , I. Ahmed 4 , S. Meiners 4
1 Electrical and Computer Engineering, Michigan State University, Lansing, Michigan, United States, 2 Department of Paper Engineering, Chemical Engineering, and Imaging, Western Michigan University, Kalamazoo, Michigan, United States, 3 Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States, 4 Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States
Show AbstractScanning Probe Recognition Microscopy (SPRM) is a new and dynamic mode of scanning probe microscopy [1,2,3]. Incorporating recognition-based tip control, SPRM can auto-track on selected regions of interest. The recognition capability is realized using algorithms and techniques from computer vision, pattern recognition, and signal processing fields. Adaptive learning and prediction make the detection and recognition procedure quicker and more reliable. SPRM improves measurements in three ways: 1) auto-tracking is performed only on regions of reliable data; 2) statistically meaningful numbers of reliable data points are extracted, providing more accurate interpretations of material characteristics; and 3) all data is extracted using an automatic procedure that maintains experimental uniformity.We are currently employing SPRM to evaluate the nanoscale biomaterial properties of a Spinal Cord Prosthetic (SCP) that is comprised of a layered array of synthetic polyamide nanofibrillar matrices prepared by electrospinning. The nanofibrillar layers within the SCP are architecturally mimetic for basement membrane and have demonstrated promise for the repair of injured spinal cord in vivo. Properties identified from these experiments that should have general relevance for the design of nanoscale devices for regenerative medicine are: 1) presentation and coverage of nanofiber associated growth factors, 2) curvature, 3) mesh density, 4) elasticity, and 5) surface roughness of nanofibers. Compiling the data of SPRM auto-tracking along individual nanofibers provides a method to develop a statistical representation of the entire nanofibrillar matrix, thus enabling the quantification and mapping of nanoscale cues that have heretofore been challenging to achieve using current AFM approaches. The development of accurate experimental and interpretive metrics will be presented for SPRM based mapping of nanoscale properties.[1] Fan, Y, Chen, Q, Ayres, VM, Baczewski, AD, Udpa, L, Kumar, S, 2007. Scanning probe recognition microscopy investigation of tissue scaffold properties. Int. J. Nanomedicine 2: 651-661.[2] Fan Y, Chen Q, Kumar S, Baczewski AD, Udpa L, Ayres VM, Rice AF, 2007. Scanning Probe Recognition Microscopy Investigation of Nanoscale Mechanical and Surface Roughness Properties Along Nanofibers, in Surface and Interfacial Nanomechanics, Editors: R.F. Cook, W. Ducker, I. Szlufarska, R.F. Antrim (Mater. Res. Soc. Symp. Proc. Volume 1021E, Warrendale, PA, 2007), 1021-HH05-26.[3] http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0400298[4] Meiners S, Ahmed I, Ponery AS, Amor N, Harris SL, Ayres V, Fan Y, Babu AN, 2007. Engineering electrospun nanofibers spinal cord repair: A discussion. Polymer Internat 56: 1340-1348. Invited manuscript for In Focus issue.
12:15 PM - OO5.3
Probing the Mechanical Properties of the Icosahedral Shell of Southern Bean Mosaic Virus with Force-probe Simulations.
Mareike Zink 1 2 , Helmut Grubmueller 2
1 Faculty of Physics and Geological Sciences, EXP I/ Soft Matter Physics, University of Leipzig, Leipzig Germany, 2 Department for Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen Germany
Show AbstractViruses are assemblies of multi-proteins forming the shell and the genetic material that is protected inside. Until now the process of self-assembly and viral infection remains unclear and the investigation of mechanical properties plays an important role here, as well as in understanding (1) How is the DNA/RNA packed inside and how can a protein shell withstand internal pressures of more than 60 atm? (2) How are the elastic properties distributed on the viral surface and how do they change before infection can take place? To address these questions, we performed force-probe molecular dynamics simulations on the complete shell of Southern Bean Mosaic Virus, a typical representative of RNA viruses with T=3 symmetry. The whole simulation system, including 1,000,000 water molecules, comprises more than 4,500,000 atoms, to our best knowledge one of the largest biomolecular simulation systems in the world. For direct comparison with recent atomic force microscopy measurements, a Lennard-Jones sphere served to mimic an atomic force microscopy (AFM) tip. This “tip-sphere” was pushed towards 19 different positions evenly distributed on the outer capsid surface. In contrast to recent AFM experiments, this technique offers the opportunity to probe the mechanical properties on much shorter length scale than usual AFM tip sizes of about 20-30 nm by reducing the tip-sphere diameter to a few nanometer. For the first time, the mechanical properties were investigated on the inner shell surface by penetrating the capsid from the viral inside. An unexpectedly heterogeneous distribution of elastic constants and yielding forces was found. The strongest elastic response was seen in the center of the pentamers at the five-fold symmetry axis. Upon calcium removal, which is supposed to be essential in viral infection, the mechanical properties of the shell were found to change markedly. In particular, an observed weakening along the five-fold symmetry axes suggests pentamers as possible exit ports for RNA release. Thus, the all-atom resolution of the model employed in this study enables a connection between capsid structures and the spatial distribution of mechanical properties that to date has not been possible.
12:30 PM - OO5.4
Frequency Modulation Atomic Force Microscope in Viruses: Resolution and Spectroscopy Improvements Under Physiological Conditions.
D. Martinez-Martin 1 , C. Carrasco 1 , P. Pablo 1 , Julio Gomez-Herrero 1 , D. Kiracofe 2 , A. Raman 2
1 , Universidad Autonoma de Madrid, Madrid Spain, 2 School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States
Show AbstractThanks to tight control on the relevant magnitudes of atomic force microscope (AFM), frequency modulation (FM) [1-3] provides atomic resolution on reactive surfaces inultra high vacuum [4]. Further developments of this mode have allowed discriminating between individual atoms on a surface alloy [5] Recently FM-AFM was introduced as ascanning mode for surfaces immersed in liquid [6], providing atomically resolved images of mica [7]. In this work we apply FM-AFM to obtain images of virus particlesunder physiological conditions with spatial resolution that approaches that obtained by X-ray diffraction and Cryo-TEM. The images show features pertaining to a single virus,which are hardly visible with the aforementioned techniques. We also present FM-AFM spectroscopy images where the elastic properties of the viruses are simultaneously measured with the topography. The mechanism involved in these images is discussed in terms of energy transfer between modes of the AFM cantilever.
OO6: SPM Manipulation
Session Chairs
Tuesday PM, December 01, 2009
Room 209 (Hynes)
2:30 PM - **OO6.1
Atomic Force Microscopy as a Tool for Atom Manipulation.
Oscar Custance 1
1 , National Institute for Materials Science, Tsukuba, Ibaraki, Japan
Show Abstract Since the first demonstration of atom-by-atom assembly at a surface [1], the manipulation of atoms and molecules has enabled the construction of model systems to explore the principles, behavior, properties, and possible functionality of nanoscale objects engineered with atomic precision. Most of these model systems were created with scanning tunneling microscopy operated at cryogenic temperatures. Recently, new prospects in our ability to manipulate matter have been opened with the possibility of manipulating atoms at surfaces using the atomic force microscope (AFM) [2-5], even at room temperature [2-4]. In this presentation, we will introduce two different methods for the manipulation of atoms with the AFM, that have yield to the creation of complex atomic patterns at surfaces [2, 3]. In the first protocol, the interaction with the AFM tip at small enough tip-surface separations produces the lowering of the natural diffusion energy barriers for the lateral interchange of atoms in the plane of a semiconductor surface, leading to well-controlled atom manipulations [2, 4]. In the second approach, atomic patterns are created by the reproducible vertical interchange of atoms between the AFM tip and the surface [3]. At variance with previous methods, these vertical interchange atom manipulations were produced by gently exploring the repulsive part of the interatomic interaction between the foremost atom of the AFM tip and the atoms to be manipulated at the surface [3]. Besides describing the experiments demonstrating these manipulation protocols, we will discuss the physics behind them and the relevant atomistic processes involved, through the analysis of the measured forces associated with these manipulations in conjunction with first-principles atomistic simulations [3-5].[1] D. M. Eigler and E. K. Schweizer, Nature 344, 524 (1990)[2] Y. Sugimoto, M. Abe, S. Hirayama, N. Oyabu, O. Custance and S. Morita, Nature Materials 4, 156 (2005)[3] Y. Sugimoto, P. Pou, O. Custance, P. Jelinek, M. Abe, R. Perez and S. Morita, Science 322, 413 (2008) [4] Y. Sugimoto, P. Jelinek, P. Pou, M. Abe, S. Morita, R. Perez and O. Custance, Phys. Rev. Lett. 98, 106104 (2007)[5] M. Ternes, C. P. Lutz, C. F. Hirjibehedin, F. J. Giessibl and A. J. Heinrich, Science 319, 1066 (2008)
3:00 PM - OO6.2
Single-Molecule Organometallic Chemistry Investigated by Low-Temperature STM.
Ingmar Swart 1 2 , Peter Liljeroth 1 3 , Sami Paavilainen 4 , Jascha Repp 2 3 , Gerhard Meyer 3
1 Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht Netherlands, 2 Institute for Experimental and Applied Physics, Faculty of Physics, Regensburg Germany, 3 IBM Research, Zurich Research Laboratory, Ruschlikon Switzerland, 4 Institute of Physics, Tampere University of Technology, Tampere Finland
Show AbstractSince their conception, scanning probe techniques – scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) – have been established as the main experimental techniques in nanoscience to get atomic scale structural and spectroscopic information. Recent experimental advances have made it possible to directly probe the delocalized molecular orbitals of organic molecules in real space [1,2]. The molecular orbital imaging is made possible by the use of an ultrathin insulating film (e.g. NaCl) that electronically decouples the molecule from the metal substrate [1,3]. The techniques that have been developed point to the possibility of using low-temperature STM as a single-molecule laboratory where the molecules are both synthesized and electronically characterized in-situ. Here, we present STM-based synthesis of an organometallic complex starting from individual metal atoms (iron and nickel) and organic molecules (dicyanoanthracene, DCA) deposited on an ultrathin insulating film. Lateral manipulation is used to form the target, linear M(DCA)2 complex. We directly visualize the frontier molecular orbitals by STM imaging. Comparison between the measured orbitals and density functional theory (DFT) calculations are used to identify the charge and spin state of the complex. In addition, we show both experimentally and theoretically how the order of the orbitals can be controlled by changing the nature of the metal atom. This is the first example of a synthesis and electronic characterization of an organometallic coordination complex on an ultrathin insulating film and demonstrates a detailed study of chemical reactivity in a STM single molecule laboratory.References[1] J. Repp, G. Meyer, S. M. Stojkovic, A. Gourdon, and C. Joachim, Phys. Rev. Lett. 94, 026803 (2005).[2] P. Liljeroth, J. Repp, and G. Meyer, Science 317, 1203 (2007).[3] X.H. Qiu, G.V. Nazin, and W. Ho, Science 299, 542 (2003).
3:15 PM - OO6.3
Manipulation of Complex Surface Adsorbed Molecules Using Scanning Tunneling Microscopy.
Corey Slavonic 1 2 , Guillaume Vives 3 , James Tour 3 , Kevin Kelly 1 2
1 Applied Physics, Rice University, Houston, Texas, United States, 2 Electrical and Computer Engineering, Rice University, Houston, Texas, United States, 3 Chemistry, Rice University, Houston, Texas, United States
Show AbstractThe STM is a valuable tool for interacting with surface adsorbed molecules on the nanometer scale. Here we use variable temperature STM to investigate two types of molecules, called Nanocars, on Au(111) substrates with the goal of controlling ever larger and complex molecular machines. These molecules contain either three or four “wheel” units made from either fullerenes or trans-alkynyl ruthenium complexes approximately 1.2 nm in diameter. Multiple dyphenyl-phosphine groups in the second type of wheel allow the molecule to be adsorbed to the Au surface, so different anisotropic surface interactions are expected depending on the number of and location of the ruthenium complexes. The molecules were dosed onto the substrate in ultra-high vacuum (UHV) conditions and subsequently imaged at room temperature. The surface was then characterized and studied at room temperature up to 170°C in UHV. Further studies were conducted by using the STM tip to directly manipulation the molecules.
3:30 PM - OO6.4
Atomically Precise Manipulation – A New Tool for Studying Hot Carrier Effects on Metal Oxide Photocatalysts.
Danda Acharya 1 , Peter Sutter 1
1 Center for Functional Nanomaterials, Brookhaven National Lab., Upton, New York, United States
Show AbstractPhotocatalysis, the acceleration of chemical reactions by photogenerated electron-hole pairs, has the potential to play a key role in renewable energy technologies. Photocatalytic water splitting on metal oxides using solar irradiation, for instance, could provide an attractive renewable source of hydrogen fuel. However, progress toward such applications remains hindered by a poor understanding of molecular-scale surface processes driven by non-thermal energy transfer from hot carriers.Cryogenic scanning tunneling microscopy can be used for the atomically precise injection of charge carriers with well-defined energy, and thus would be a powerful tool to simulate charge transfer effects in photocatalysis. We have for the first time successfully applied the controlled local excitation by tunneling electrons to study elementary chemical reaction steps on oxides, in particular those involved in photocatalytic water splitting on TiO2. On rutile TiO2(110), tunneling electrons have been used to dissociate individual water molecules, and to desorb hydrogen atoms bound to bridging oxygen sites. Tunneling electrons were also used to drive the controlled hopping of individual bridging oxygen vacancies, thus enabling the construction of nanometer-scale arrays of these reactive sites by single vacancy manipulation. We discuss measurements of threshold energies defining the onset of these reaction steps, as well as the identification of the effects of hot carriers, which range from simple vibrational heating to dissociative electron attachment of multiple charge carriers. Overall, the ability to drive surface processes by atomically precise charge injection provides unprecedented insight into the mechanisms of heterogeneous photocatalysis.
3:45 PM - OO6.5
Investigating Nanomachine Motion with Variable Temperature STM.
JungHo Kang 1 , Guillaume Vives 2 , James Tour 2 , Kevin Kelly 1
1 Electrical and Computer Engineering, Rice University, Houston, Texas, United States, 2 Department of Chemistry, Rice University, Houston, Texas, United States
Show AbstractScanning tunneling microscopy (STM) is an essential tool in characterizing molecular motion on surfaces because of its capability in imaging and manipulating individual atoms and molecules. Various chemo-mechanical systems such as molecular motors, elevators, and turnstiles, etc. have previously been synthesized and tested; however, very few have been probed at the molecular level. Building upon our previous research, nanocars with a wide-range of structures were synthesized and studied by STM. Previously reported nanocars with fullerene wheels have shown rolling motion on Au(111) surfaces when thermal energy was applied. For better understanding of the relationship between the motion and the wheel structure, we compare the behaviour of fullerene wheels with those composed of p-carboranes. Using variable temperature STM, we are able to observe differences in motion due to both surfaces interactions and changes in intramolecular structure.
4:30 PM - **OO6.6
Atomic Scale Spin-transfer and Lifetimes of Quantum Spins.
Sebastian Loth 1
1 Research Center, IBM - Almaden, San Jose, California, United States
Show AbstractControlling the flow of electrons through a conductive material with the material’s magnetization is the basis of the giant magneto-resistance effect (GMR) and the tunnel magneto-resistance effect (TMR). Their technological application has led to vastly improved storage capacities of magnetic data storage devices [1]. The inverse effect, spin transfer torque (STT), allows one to influence a magnetic layer by high current densities of spin-polarized electrons even culminating in the current-induced switching of its magnetization direction. STT carries high hopes in technical application for solid-state, non-volatile memory [2]. We show that equivalent processes are active in quantum spin systems. As model systems we investigate transition metal atoms adsorbed to a copper nitride layer grown on a Cu substrate. Individual atoms or nanostructures consisting of only a few magnetic atoms exhibit well-defined spin states which are described by spin Hamiltonians that account for Zeeman energy, magneto crystalline anisotropy and spin-spin coupling [3]. As opposed to magnetic layers, a quantum spin’s orientation of magnetization cannot be determined in all three spatial directions at the same time. The magnetization is described by its projection to a given quantization axis, the magnetic quantum number m. In order to address the magnetic structures individually, we use a scanning tunneling microscope (STM) operating at low temperature (0.5K) and high magnetic field (7T) and probe the structure’s spin excitations by inelastic electron tunneling [3]. Spin polarized current emitted from a spin-polarized probe tip efficiently transfers spin angular momentum to the atomic spin system. High current densities pump the spin system between the different spin states. Analogous to the macroscopic STT the direction of current flow decides whether the atom’s magnetic moment is driven towards alignment with the probe tip’s magnetization, i.e., towards positive m quantum number states, or towards anti-alignment, into negative m states. Being able to sense and control the magnetization of a quantum spin system by purely electrical means opens a way to study the lifetimes of excited spin states and the corresponding relaxation effects.[1] Wolf et al., Science 294, 1488 (2001).[2] Huai, AAPPS Bulletin 18, 33(2008).[3] Hirjibehedin et al., Science 312, 1021 (2006) & Science 317, 1199 (2007).
OO7: Poster Session
Session Chairs
Wednesday AM, December 02, 2009
Exhibit Hall D (Hynes)
9:00 PM - OO7.1
Conductive Atomic Force Microscopy and Scanning Impedance Microscopy for the Imaging of Electrical Domain in CaCu3Ti4O12 Perovskite Oxide.
Raffaella Lo Nigro 1 , Patrick Fiorenza 1 , Vito Raineri 1
1 , IMM-CNR, Catania Italy
Show AbstractRecently, studies on the calcium copper titanate, CaCu3Ti4O12 (CCTO), have revealed that this material possesses an impressive giant dielectric constant value of 105 times the vacuum permittivity ε0 at 1MHz, which remains constant in the 100-600 K temperature range and depends slightly on the frequency in the 102-105 Hz range. In addition, CCTO does not show ferroelectric transition. These interesting properties render the CCTO a real attractive alternative material to the currently used ferroelectrics which in turn possess lower dielectric constant values having stronger temperature dependence.The presence of domains with different electrical characteristic represent one of the most important and possible explanation for the extrinsic origin of the CCTO colossal dielectric response. This paper reports on the electrical characterization of CCTO ceramics with scanning probe based techniques. Previous works highlighted the importance of scanning probe microscopy (SPM) based techniques to investigate the conduction and insulating behaviours of heterogynous materials. In this context, conductive atomic force microscopy and scanning impedance microscopy have been used to demonstrate the presence, shape and size in CCTO ceramics, having different grains dimension, of the different electrically domains, both at the grain boundaries and within the grains.In particular, the possibility to extrapolate the electrical characteristics of the single grain and of the single domain has been evaluated considering the insulating grain embedded in a conductive matrix. Furthermore, the conductivity of both the insulating and conductive domains has been obtained.
9:00 PM - OO7.10
Nanoscopic Characterization of Hysteretic and Rectifying Metal/Oxide Schottky Junctions.
Haeri Kim 1 , Soo-Hyon Phark 1 , Dong-Wook Kim 1 2
1 Department of Physics, Ewha Womans University, Seoul Korea (the Republic of), 2 Department of Chemistry and Nano Science, Ewha Womans University, Seoul Korea (the Republic of)
Show AbstractWe investigated electrical properties of junctions consisting of metal electrodes and oxide (TiO2 and SrTiO3) single crystals. The junctions formed with large work function metals (Ni, Au, Pd, and Pt) exhibited hysteretic and rectifying transport behaviors [1]. Conventional Schottky diode model failed to explain the current-voltage characteristics, since the estimated Richardson constant was too small. The temperature-dependence of the barrier height and the ideality factor showed that the inhomogeneous barrier model well described the experimental data [2]. This suggested that nano-scale characterization of the junctions should be useful for better understanding. Thus, the charge and current distributions of the junctions were examined using scanning probe microscope (SPM). Biased SPM tips were also used as moving electrodes and resulting alteration of the local properties were studied. The results indicated that the ionic migration and barrier height alteration at the interfacial region could affect the characteristics of the junctions.[1] C. Park et al., J. Appl. Phys. 103, 054106 (2008).[2] H. Kim et al., J. Phys. D: Appl. Phys. 42, 055306 (2009).
9:00 PM - OO7.11
Reference Structures for Electrical Scanning Probe Microscopy.
Stefan Weber 1 , Maria Retschke 1 , Matthias Fenner 2 , Hassan Tanbakuchi 2 , Maren Mueller 1 , Hans-Juergen Butt 1 , Ruediger Berger 1
1 , Max Planck Institute for Polymer Research, Mainz Germany, 2 , Agilent Technologies GmbH, Kronberg Germany
Show AbstractWith recent progress in the area of molecular electronics, the characterization of electrical properties on small length scales becomes more and more important. In research and industry, films made from composite materials and lithographically structured elements have already reached structure sizes down to a few nanometers. With scanning probe microscopy (SPM) methods a variety of electrical modes are known and used to map surface properties on a nanometer scale [1]. To demonstrate the potential of SPM based electrical modes we fabricated reference samples by means of focused ion beam (FIB) assisted chemical vapour deposition on different substrates. We fabricated crossed bar structures made from two different materials: an electrically insulating SiO bar (insulator deposition) on top of a platinum metal bar (Pt-deposition) and a second structure with the metal on top of the insulator. The outer dimensions of the bars are 30µm x 1µm. Such reference samples have defined elevated features, 10-50 nm in height, and therefore can help to clarify and understand possible topographic crosstalk with the locally recorded electrical signal. We will compare the results of the most common electrical modes in scanning probe microscopy on the reference cross bar structures, namely conductive scanning force microscopy (CSFM), Kelvin probe force microscopy (KPFM) and scanning electric field microscopy (EFM). Furthermore, two upcoming modes are presented: (i) scanning conductive torsion mode microscopy (SCTMM) maps local conductivity variations during non-contact torsion mode imaging of the surface. (ii) Scanning microwave microscopy (SMM) observes changes in the backscattering behavior of microwaves coupled into a SPM-cantilever tip in contact with the sample surface, which gives insights to the local doping levels and the dielectric structure [2]. By investigating the same individual structure with several SFM modes, different material properties (conductivity, workfunction, dielectric constant, etc.) could be readily associated with the predefined crossed bar structure. Specific effects of the different modes could be identified, for example local damaging of the surface during C-SFM imaging which did not occur during SCTMM imaging of the same spot. Moreover, issues associated with the focused ion beam preparation process of the reference structures, namely carbon contaminations in the insulator and metal stripes and small traces of species close to the cross bar structure (overspray) were addressed. [1] Berger, R., Butt H.-J., Retschke, M., Weber, S.A.L., Electrical Modes in Scanning Probe Microscopy, Macromol. Rapid Comm. 2009, 30.[2] Karbassi, A., et al., Quantitative scanning near-field microwave microscopy for thin film dielectric constant measurement. Review of Scientific Instruments, 2008. 79(9).
9:00 PM - OO7.2
Frequency Dependent Kelvin Probe Force Microscopy on Locally Doped Si.
Christine Baumgart 1 , Manfred Helm 1 , Heidemarie Schmidt 1
1 Institute of Ion-Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, Dresden, Sachsen, Germany
Show AbstractFailure analysis and optimization of nanoelectronic devices require knowledge of their electrical properties. Kelvin probe force microscopy (KPFM) is a standard technique for the investigation of the surface potential. We present its applicability to buried doped regions in cross-sectionally prepared Si epilayer structures and to shallow doped regions in a conventional dynamic random access memory (DRAM) cell. Frequency dependent KPFM measurements were performed under ambient conditions by means of an Anfatec Level-AFM with a 2nd amplifier and p- and n-type conductive NSC15 probes from MikroMasch. Using an active mixer, the excitation amplitude of the NSC15 probes is almost independent of the operation frequency. The frequency dependence of the Kelvin bias above differently doped regions is discussed with respect to surface states and trapped charges in the thin oxide layer. As a result, KPFM measurements have to be performed at frequencies high enough so that the electrical properties of the locally doped Si are probed.
9:00 PM - OO7.3
Scanning Thermal Microscopy of Optoelectronic Polymer Thin Films.
Lung Chen 1 , Chun-Min Huang 1 , De-An Huang 1 , Changshu Kuo 1 2
1 Department of Materials Science and Engineering, National Cheng Kung University, Tainan Taiwan, 2 Center for Micro/Nano Science and Technology, National Cheng-Kung University, Tainan Taiwan
Show AbstractA novel technique based on the scanning thermal microscopy (SThM) was developed to provide the surface morphology and thermal behaviors of optoelectronic organic thin films. Poly(3-hexylthiophene) (P3HT) and methanofullerene derivative (PCBM), used in bulk heterojunction photovoltaics, were spin-coated on silicon wafers or ITO-coated glasses with film thicknesses ranged from 50 to 900 nm. Thermal expansion profiles of nano-scale thermal probes indicated the thermal expansion coefficients and the melting temperatures of P3HT/PCBM samples were both affected by film thicknesses. A series of SThM with various scanning temperatures was conducted to establish the 2D mapping of surface thermal conductivities. Fluctuations of these thermal conductivities revealed the thermal transitions and/or the phase separations near the material surfaces. Thermal conductivity fluctuations were maximized at the mapping temperatures of about 80C and 120C for pure P3HT and P3HT/PCBM samples, respectively. The first one represented the 80C glass transition temperature of P3HT, which was usually undetectable in the differential scanning calorimetry. And, the 120C temperature recognized the optimized thermal annealing of P3HT/PCBM blends, where the phase separation of P3HT and PCBM altered the distribution of surface thermal conductivities.
9:00 PM - OO7.4
Generalized Active Quality Factor Control of Electromechanical Quartz Resonator and their Applications.
Junghoon Jahng 1 2 , Manhee Lee 1 , Wan Bak 1 , Wonho Jhe 1
1 , Department of Physics and Astronomy, Seoul National University, Seoul Korea (the Republic of), 2 , Condensed Matter Research Institute, Seoul National University, Seoul Korea (the Republic of)
Show AbstractWe present generalized theoretical analysis and experimental realization of active quality factor control for the self-oscillating quartz tuning-fork (QTF). The quality factor Q and resonance frequency can be controlled by adding a phase shifted signal of proper gain with respect to the QTF motion. It is demonstrated that the analysis of QTF can be extended to other quartz resonators which are analyzed by an equivalent circuit-a combination of a parallel circuit of an harmonic L-R-C and a stray capacitance C0. Then, we suggest the prospect of several applications by using the active Q control such as increasing force sensitivity, feedback cooling of electromechanical resonator.
9:00 PM - OO7.5
High Resolution Electrostatic Force Microscopy by Multifrequency Technique Under Ambient Environment.
Ding Xi Dong 1 2 , An Jin 1 , Xu Jian Bin 1
1 Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China, 2 State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics Sciece and Engineering, , Sun Yat-Sen University, Guangzhou, 510275 China
Show AbstractA multifrequency scanning probe technique which can enhance the spatial resolution of electrostatic force microscopy (EFM) in amplitude-modulation (AM) mode under ambient conditions is demonstrated. The first eigenmode of a cantilever is used for topographic imaging in the first scan, while the second eigenmode is resonantly excited with a sinusoidal modulation voltage applied to the cantilever to measure electrostatic force in lift mode. Two-dimensional images and spectra of electrostatic force are obtained. In comparison with other conventional EFM operated in ambient environment, the lateral resolution of the multifrequency EFM is demonstrated to be better than 15 nm and a better signal-to-noise ratio is achieved. Finally, a theoretical explanation is postulated.
9:00 PM - OO7.6
Measurement of the Interaction Force Necessary to Displace Pentacene Layers on Ag(111).
Shawn Huston 1 , Rachel Port 1 , Pengshun Luo 1 , Thomas Pearl 1
1 Physics, North Carolina State University, Raleigh, North Carolina, United States
Show AbstractPentacene is one of the most promising p-type organic semiconductors for use in organo-electronic devices. As such, it is important to understand the role that the electrode-pentacene thin film interface plays in determining thin film electronic properties. Previously it has been found through scanning tunneling microscopy (STM) studies that pentacene monolayers on Ag(111) show high mobility at room temperature on Ag(111). In addition, pentacene thin films show surprising mobility on Ag(111) even at 77 K. Interaction of pentacene with an STM tip leads to changes in the morphology of the thin film such as dramatic movement and restructuring of pentacene islands. We here attempt to quantify the interaction force between pentacene layers and the underlying surface through non-contact atomic force microscopy (NC-AFM). Of particular interest is the relative difference in interfacial mobility of pentacene monolayers sliding on the metal lattice in contrast to sliding between layers of pentacene in the bilayer. These measurements provide an excellent display of the utility of our recently designed Besocke-style scanning probe microscope which has both frequency modulated atomic force and scanning tunneling microscopy capabilities. This instrument has been optimized for use at low temperatures, either with helium or nitrogen cooling, in ultrahigh vacuum. FM-AFM is performed via a quartz crystal tuning fork in the qPlus sensor configuration. This Besocke-style microscope is designed to record tunneling current and resonance frequency shift simultaneously for a conductive tip mounted on the free prong of the tuning fork.
9:00 PM - OO7.7
Design of a Variable Temperature Variable Magnetic Field Noncontact Scanning Force Microscope for the Characterization of Nanoscale Electronic and Magnetic Phenomena.
Peter Staffier 1 2 , Jens Falter 1 , Nicolas Pilet 1 2 , Marcus Liebmann 1 , Charles Ahn 3 2 , Udo Schwarz 1 2
1 Department of Mechanical Engineering, Yale University, New Haven, Connecticut, United States, 2 Center for Research on Interface Structures and Phenomena (CRISP), Yale University, New Haven, Connecticut, United States, 3 Department of Applied Physics, Yale University, New Haven, Connecticut, United States
Show AbstractIn thin film manganese oxides variations in the electric charge carrier density can result in increased conductivity, magnetic domain formation, and lattice distortions due to strong electron correlation effects. We intend to characterize the length scales at which the electronic, magnetic, and structural properties of thin films of La[1-x]Sr[x]MnO[3] remain correlated by using localized electrostatic fields to modulate the electric charge density while applying noncontact scanning force microscopy methods to observe the resulting phase changes. Since manganese oxides are most sensitive to electrostatic perturbation near their phase transition temperatures Tc, a critical part of the planned experiments will be to measure samples at various temperatures.For that purpose, we have developed a new ultrahigh vacuum variable temperature noncontact scanning force microscope (NC-AFM). The requirement to run experiments at distinct, stable temperatures slightly below and above Tc has been addressed by choosing a low vibration flow cryostat for cooling. Thermal gradients are minimized by cooling the entire microscope, in contrast to most commercially available variable temperature NC-AFMs. In addition, an electromagnet mounted to the vacuum system supplies magnetic fields up to 180 mT for in-field magnetic force measurements. A quartz microbalance and two evaporators allow for the preparation of multilayer magnetic force sensors in-situ. Both cantilever and sample stages permit the exchange of force sensors and samples in-situ with the microscope at low temperatures. An x-y translation stage provides up to 4 mm × 4 mm of course motion in the horizontal plane so that we may measure at various positions on the sample. We will present the microscope’s design, initial measurements in topographical and magnetic operational modes, and details on some of the further planned experiments.
9:00 PM - OO7.8
Force and Tunneling Current Measurements on the Semiconductor Surface.
Ken-ichi Morita 1 , Sawada Daisuke 1 , Yoshiaki Sugimoto 1 , Masayuki Abe 1 , Seizo Morita 1
1 , osaka university, Suita Japan
Show AbstractNon-contact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM) enable us to obtain atomically-resolved information, for example, chemical bonding force or local density of state (LDOS). Recently, at the near contact region, the drop of the tunneling current was reported using conventional STM [1]. The drop of the tunneling current was explained by the chemical bonding formation, however, such correlation has not been measured experimentally. We measured the force and the tunneling current simultaneously using metal coated Si cantilevers. Here, we report our results on both the Si(111)-(7×7) surface and the Ge(111)-c(2×8) surface at room temperature using the feedforward technique in order to compensate the thermal drift [2].In constant height simultaneous measurement, atomic image contrast between the AFM image and the STM image are different. We obtained F-z and I-z curves on the adatom of the Ge(111)-c(2×8) surface by measuring df-z and I-z curves. The drop of I was oabserved at the onset of FSR with decreasing the tip-surface distance. The drops were observed on the Ge(111)-c(2×8) surface as well as the Si(111)-(7×7) surface [3].[1] P. Jelínek, et al., Phys. Rev. Lett. 101, 176101 (2008). [2] M. Abe, et al., Appl. Phys. Lett. 90, 203103 (2007).[3] D. Sawada, et al., Appl. Phys. Lett. 94, 173117 (2009).
9:00 PM - OO7.9
AFM/STM Simultaneous Measurement on TiO2 (110) Surface.
Hideki Tanaka 1 , Ayhan Yurtsever 1 , Yoshiaki Sugimoto 1 , Masayuki Abe 1 , Seizo Morita 1
1 Graduate school of Engineering , Osaka University, Osaka Japan
Show AbstractScanning tunneling microscopy (STM) [1] and non-contact atomic force microscopy (NC-AFM) [2] are used as typical surface analysis tools with atomic resolution in real space. STM measures tunneling current between tip and sample, while NC-AFM, which is suitable for insulator, used the frequency shift to detect interaction force between tip and sample indirectly. By using a conductive tip with NC-AFM, simultaneously AFM and STM operations are possible [3].Titanium dioxide (TiO2) is one of the typical metal oxides which has many applications in technology such as electronic devices, catalysts, and sensors [4]. By vacuum annealing, oxygen vacancies are created, this induces the conductivity of the surface. For this reason, both STM and AFM can be applied. Our experiments were conducted in AFM/STM, which measures both the frequency shift and the tunneling current simultaneously in constant height mode. Using the constant height mode, the crosstalk between the frequency shift and the tunneling current signals can be eliminated. In positive sample bias STM images, the tunneling site is found on the titanium atoms rather than bridging oxygens [5]. However, in NC-AFM, three types of imaging contrast which are assigned as negative tip, neutral tip, and positive tip are usually obtained on this surface [6]. These contrasts strongly depend on the polarity of tip-apex and atomic-scale configuration.We have successfully obtained a new type of the frequency shift (AFM) image which has no OH defects on the surface at room temperature for the first time. We named this new image contrast as “hidden mode” image of TiO2 (110) surface. Here, the surface patterns brightness and darkness can not be clearly identified whether the titanium or oxygen rows imaged as protrusions. We have simultaneously measured tunneling current image (STM) which exhibit OH in between bright Ti rows. Since both the frequency shift and tunneling current images are measured at the same place, we are able to identify which atomic rows are imaged as bright stripes in hidden mode by comparing these images.AFM/STM simultaneous measurement with constant height mode becomes a powerful tool to characterize metal oxide surfaces as like TiO2. We will discuss the imaging mechanism of TiO2(110) using AFM/STM at room temperature.References[1] G. Binning et al.,Phys.Rev.Lett,50,120(1982)[2] T. R. Albrecht et al.,J.Appl.Phys,69,688(1991)[3] D. Sawada et al.,Appl.Phys.Lett,94,173117(2009)[4] V. E. Henrich et al.,Cambridge.Univ.Press,Cambridge(1996)[5] S. Wendt et al.,Surf.Sci.598,226 (2005)[6] G. H. Enevoldsen et al.,Phys.Rev.B.76,205415(2007)
Symposium Organizers
Ruben Perez Universidad Autónoma de Madrid
Suzi Jarvis University College Dublin
Seizo Morita Osaka University
Udo Schwarz Yale University
OO8: Oxides
Session Chairs
Wednesday AM, December 02, 2009
Room 209 (Hynes)
9:15 AM - **OO8.1
Understanding and Manipulating Oxide Surfaces at the Atomic Scale.
Michael Reichling 1
1 , Universitaet Osnabrueck, Osnabrueck Germany
Show AbstractMetal oxide materials are widely used in industrial areas like catalysis, sensors, microelectronics, energy conversion and many other present or foreseen fields of technology development. In many of their applications, the surface structural, compositional and chemical properties play a crucial role for the functionality of a device based on an oxide and fundamental studies on atomic scale structures and processes on their surfaces can greatly contribute to an understanding and development of oxide materials.It will be demonstrated how dynamic scanning force microscopy operated in the non-contact mode (NC-AFM) can provide detailed information on surface structural details, defects and adsorbed layers where a clear identification of surface features is facilitated by extended theoretical modelling. It will also be shown how the tip of the force microscope can be used for the controlled atomic scale manipulation on oxide surfaces performed at various temperatures including room temperature. The capabilities of advanced dynamic force microscopy in this field will be elucidated for the examples of pristine, defective and adsorbate covered CeO2(110) and TiO2(001) surfaces.
9:45 AM - OO8.2
Study of TiO2 (100) 1 × 1 and 1 × 3 Surfaces by Non-contact Scanning Nonlinear Dielectric Microscopy Combined with Scanning Tunneling Microscopy.
Nobuhiro Kin 1 , Yasuo Cho 1
1 , Tohoku University, Sendai Japan
Show Abstract Scanning nonlinear dielectric microscopy (SNDM) is a pure electrical method that is used for detecting the local anisotropy of dielectric materials and for measuring ferroelectric polarization at sub-nanometer resolutions. Recently, we have developed non-contact SNDM (NC-SNDM) with a height control technique that can be used to detect a higher-order nonlinear dielectric constant (ε(4) signal). We have already succeeded in observing the typical Si (111) 7 × 7 and Si (100) 1 × 2 atomic structures [1, 2]. Rutile TiO2 has been studied extensively because it is a well-known insulating material and is widely used as a superior substrate for investigating the surface physics of metal oxides. It is well known that TiO2 becomes an n-type semiconductor after high-temperature annealing under ultrahigh vacuum conditions. Due to its simplicity, the atomic structure of TiO2 can be examined easily as compared to that of other insulating materials such as SrTiO3, which comprises three types of atoms. Therefore, in this study, we selected TiO2 as our initial specimen for investigating insulating materials by NC-SNDM. Most of the previous studies have been carried out using (110) surfaces. In this study, we have selected a (100) surface and have attempted to understand in detail how the surface would be reconstructed by annealing in different temperature ranges and also by a combination of such annealing and Ar+ sputtering. In conclusion, several types of surface structures can be observed by a combination of both STM and NC-SNDM. In most cases, parallel bright stripes corresponding to Ti4+ can be observed in the [001] direction. In some cases, the surface structure is changed to 1 × 3 structure, and the 1 × 3 atomic structure and {110} micro-facetted surface can be clearly observed at atomic resolutions.[1] Y. Cho and R. Hirose, Phys. Rev. Lett. 99, 186101 (2007).[2] N. Kin, Y. Osa and Y. Cho, Journal of Applied Physics 106 (2009), to be published.
10:00 AM - OO8.3
Understanding the Mechanism of Different Contrast Modes on TiO2 (110)-(1x1) Surface using nc-AFM at Low Temperature-a Force Spectroscopic Measurement.
Abdi Pratama 1 , Ayhan Yurtsever 1 , Yoshiaki Sugimoto 1 , Masayuki Abe 1 , Seizo Morita 1 , Pavel Jelinek 2 , Cesar Gonzalez 2 , Ruben Perez 3
1 Graduate School of Engineering, Osaka University, Osaka Japan, 2 Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka, Prague, Czechia, 3 Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid Spain
Show AbstractNon-contact atomic force microscopy (nc-AFM) is powerful tool for characterizing and manipulating [1] conducting as well as nonconducting materials.Titanium oxide is the most widely studied single crystal metal-oxide surface. Due to its useful applications in catalyst, solar cells, protective coatings, and gas sensing devices, it has led to extensive research on this surface. Using the defects such as OH groups and oxygen vacancies as a marker, the surface patterns brightness or darkness indicating the interaction strength between tip and surface can be identified [2]. In general, imaging contrast of metal-oxide surfaces strongly depends on the chemical constitution of the surface and chemical identity of the tip apex. Occasionally, different tip states are obtained by the tip changed during the scanning which is most likely caused by the accumulation of surface atoms on the tip-apex or the relaxation of tip-apex atoms itself. Three types of imaging contrast modes are commonly obtained, which are assigned as negative tip, neutral tip, and positive tip [3]. However, still many different images contrast are also obtained. Understanding the source of the contrast is still incomplete on this surface. For example, we have successfully obtained a new type of image contrast which has no defects that mostly appear in common images. We named this new type of images as “hidden mode” image of TiO2(110) surface. At close-range tip-sample distances, we are also able to resolve in-plane oxygen atoms of the surface. These results show that imaging mechanism is not only depending on the polarity of the tip-apex but also the property of the chemical bonding force. To understand the imaging mechanism of these different contrast modes, the measurement of force versus distance relationship over specific atomic sites is needed.We have successfully measured the site-specific force spectroscopy on this surface at low temperature for the first time. Our measurements show that measured forces reveal significant difference for each contrast mode. For a positively terminated tip, the maximum attractive force is comparable with different sites, e.g Ti, Ob and OH, whereas, with a negatively terminated tip, the maximum attractive force at Ob and Ti sites indicates remarkable difference with those of OH sites. In this contribution, we will discuss the imaging mechanism of TiO2(110) surface using nc-AFM at low temperature by combining first principles calculations to understand the effect of tip-apex states on the observed image contrasts by considering different aspect of tip apex terminationReferences[1] Sugimoto Y, Abe M, Hirayama S, Oyabu N, Custance O and Morita S 2005 Nature Mater. 4 156[2] G. H. Enevoldsen et al., Phys. Rev. B 78, 19 (2008).[3] G. H. Enevoldsen, et al., Phys. Rev. B. 76, 205415 (2007)
10:15 AM - OO8.4
Character of the Short-range Interaction between a Silicon Based Tip and the TiO2(110) Surface: a DFT Study.
Cesar Gonzalez 1 2 , Pavel Jelinek 2 , Ruben Perez 3
1 Superficies y recubrimientos, Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Madrid, Spain, 2 Thin Films, Institute of Physics of the ASCR, Prague, Prague, Czechia, 3 Fisica Teorica de la Materia Condensada, Facultad de Ciencias, UAM, Madrid, Madrid, Spain
Show AbstractNon-contact atomic force microscopy (NC-AFM) provides a rich variety of atomic contrasts on the rutile TiO2 (110) surface, imaging either the bridging oxygen atoms (hole mode) or the titanium atoms (protrusion mode) [1]. These contrast modes have been assigned to purely electrostatic interaction. Another contrast mode that does not fit into the scheme of purely electrostatic interaction, the so-called neutral mode, has also been reported [2]. Recently it has been demonstrated that NC-AFM is capable of imaging both, the bridging oxygen atoms and the titanium rows simultaneously in a new all inclusive mode [3]. Such diversity of contrast modes can be attributed to the complex character of the short range interaction between tip and characteristic sites of the rutile TiO2 (110) surface driven by (i) a weak short-range electrostatic interaction [4] depending on atomic termination of tip and its polarization and (ii) the onset of chemical bond formed between a tip and surface [5]. A proper characterization of the different regimes in the short-range interaction regime Si-based tips and this oxide surface is crucial for the interpretation of the experimental images and the design of protocols for single atom manipulation and chemical identification.Here we have employed density-functional theory (DFT) calculations to understand the character of tip-sample interaction between clean and contaminated Si-based tips and the TiO2 surface. We have performed a detailed analysis of electronic structure and the charge transfer between tip and sample. Our calculations show that the relative contribution of the weak short-range electrostatic interaction and the onset of chemical bonding between the closest tip and surface atoms is very sensitive to the tip-sample distance, defining different interaction regimes along the tip-sample distance. In particular, we show the short-range electrostatic interaction in weak interaction regime can provide a complex atomic contrast such as the experimentally reported neutral and all-inclusive contrast modes.[1] J. A. Smith, M. B. Example, and M. Mustermann. Nature 123, 456 (2009). [1] J.V. Lauritsen et al. Nanotechnology 17, 3436 (2006).[2] G.H. Enevoldsen et al. Phys. Rev. B 78, 045416 (2008).[3] R. Bechstein et al (submitted).[4] A.S. Foster et al. Phys. Rev. B 68, 195420 (2003).[5] R. Pérez et al. Phys, Rev. B 58, 10835 (1998).
10:30 AM - **OO8.5
High-Resolution Atomic Force Microscopy (AFM) of Catalytic Model Systems.
Flemming Besenbacher 1
1 Interdisciplinary Nanoscience Center (iNano), Arhaus University, Aarhus C Denmark
Show AbstractThe development of renewable, sustainable and green energy resources and the protection of the environment by reducing emission pollutants are two of the largest challenges for the human civilization within the next 50 years. Besides the well-known energy resources that power the world today; petroleum, coal, and natural gas, active research and development exploring alternative energy resources such as solar, biomass, wind, and hydrogen is currently being done. Research and innovation within the rapidly expanding field of nanoscience is mandatory to make the vision of a clean society and plentiful, low-cost sustainable energy a reality.For decades single-crystal surfaces have been studied under ultra-high vacuum (UHV) conditions as model systems for elementary surface processes. This “surface science approach” has contri-buted substantially to our understanding of the processes involved in especially catalysis. In this talk I will show how atom-resolved dynamic-mode Atomic Force Microscopy (or non-contact AFM) can be used to study model oxide catalytic relevant support systems such as Al2O3 and ZnO. Due to the insulating nature of these oxide surfaces relatively little is known about the detailed surface structure and in particular the role of its atomic defects. Using an interplay between nc-AFM studies and density functional theory (DFT) calculations, we have obtained novel atomic-scale insight into the intriguing √31×√31R°9 reconstructed state of α-Al2O3(0001). The distinct sub-domains revaled by nc-AFM arise due to variations in the stacking between a single atomic Al layer on top of an Al-rich Al2O3(0001) substrate (so-called Al-Al-O-Al2O3), leading to a sub-Å modulation of the perpendicular Al-distance relative to the substrate. Furthermore, we have shown that profound structural differences exist between the oppositely terminated, polar low-index ZnO(0001) surfaces, which are linked to a higher flexibility of bond-ing of surface atomic Zn species compared to O. From our findings, we provide a description of the key atomistic principles governing the stabilization of such polar surfaces.
OO9: Mechanical Properties
Session Chairs
Wednesday PM, December 02, 2009
Room 209 (Hynes)
11:30 AM - OO9.1
Probing Nanomechanics and Nonlinearities Using Band Excitation Scanning Probe Microscopy.
Stephen Jesse 1 , Sergei Kalinin 1
1 The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show AbstractProbing elastic moduli, loss moduli, and non-linear tip-surface interactions on the nanometer scale is one of the key challenges in nanomechanics. Here, we present a universal and quantitative approach for mapping local loss moduli on the nanometer scale based on dynamic scanning probe microscopy. In most SPMs, the cantilever is excited to oscillate sinusoidally and the time-averaged amplitude and/or phase are used as imaging or control signals. The step of converting the rapid motion of the cantilever into an amplitude or phase is performed by phase sensitive homodyne or phase-locked loop detection. In this presentation, I discuss the fundamental limitation of lock-in detection as applied to probing energy dissipation and complex cantilever dynamics, and introduce the band excitation method (BE). The BE method is based on the excitation and detection of a signals having a finite amplitude over a selected region in the Fourier domain. The detected signal is Fourier transformed and fit by an appropriate model to extract multiple properties describing nanoscale mechanics simultaneously. This data acquisition scheme substitutes standard lock-in or PLL detection. This band excitation (BE) SPM allows very rapid acquisition of the full frequency response at each point in an image and in particular enables the direct measurement of energy dissipation through the determination of the Q-factor of the cantilever-sample system. Furthermore, knowledge of the full spectral response of the cantilever provides the ability to detect the onset and nature of anhamonic tip-surface interactions. We demonstrate this technique with electromechanical imaging, the investigation of dissipative defects in magnetic force microscopy, and in force-distance spectroscopy. The BE method thus represents a new paradigm in SPM, beyond traditional single-frequency excitation and is applicable as an extension to many existing SPM techniques.Research was sponsored by the the Center for Nanophase Materials Sciences, Office of Basic Energy Sciences, U.S. Department of Energy with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC.
11:45 AM - OO9.2
Pushing the Limits of Resolution in Material Property Mapping with Atomic Force Microscopy.
Bede Pittenger 1 , Chanmin Su 1 , Natalia Erina 1 , Shuiqing Hu 1
1 , Veeco Metrology, Santa Barbara, California, United States
Show AbstractMacroscopic material performance is often strongly influenced by the local material properties and the extent of interphase boundaries in polymer blends and other composites. Since the dimensions of the component domains and the boundaries are often sub-micron, the Atomic Force Microscope (AFM) is a natural tool to study them.TappingMode™ Phase Imaging, dual frequency, and single harmonic tapping have some ability to map non-topographic properties of the sample, allowing discrimination between different components in composite systems, but they cannot separate the influence of different material properties such as modulus and adhesion. Until now, researchers have been forced to rely on much slower, lower resolution techniques such as nanoindentation and force volume for quantitative material property information.The recently introduced HarmoniX™ microscopy technique provides independent, quantitative nanoscale mapping of material properties such as elasticity, adhesion, and energy dissipation. By simultaneously analyzing the full spectrum of motion of special probes designed for high bandwidth force measurements, HarmoniX produces force-distance curves that represent the variation in tip-sample force that occurs when the tip goes through a period of tapping oscillation. These curves are then analyzed to obtain the material properties of the sample. HarmoniX microscopy is hundreds of times faster than other quantitative material mapping techniques such as force volume, but retains the high resolution, non-destructive qualities of TappingMode Imaging.In this talk we will discuss new advances that have significantly improved the resolution and quantitative material property measurement capabilities of the AFM as applied to polymers and polymer composites. The accuracy of mechanical measurements was verified by traditional AFM indentation with well-calibrated cantilever spring constant and tip radius. We will also discuss the application of these advances to other materials with detailed nanostructures, such as molecular monolayers and biomaterials.
12:00 PM - OO9.3
Investigation of Particle-Polymer Interactions in Nanocomposites via SPM-based Characterization.
Meng Qu 1 , Jeffrey Meth 2 , Gordon Cohen 2 , Kenneth Sharp 2 , Agathe Robisson 3 , Gregory Blackman 2 , Krysytn Van Vliet 1
1 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 CR&D, DuPont Nanocomposite Technologies, Wilmington, Delaware, United States, 3 , Schlumberger-Doll Research and Development, Cambridge, Massachusetts, United States
Show AbstractNanocomposites comprising polymer matrices and nanoparticle fillers can exhibit unique mechanical and physical properties that are not predicted by two-phase composite models. This emergent behavior is posited on the possible existence of an interphase polymer region at the matrix-particle interface, such that this the particle-polymer interaction might play an important role on the overall properties of nanocomposites. However, it has been historically difficult to demonstrate the existence and properties of such a nanoscale interphase interaction through direct experimental methods. Here, we discuss two approaches to probe the interphase particle-polymer interactions via scanning probe microscopy (SPM)-based techniques. First, we demonstrate visualization and characterization of the particle-polymer interface via the HarmoniX torsional AFM technique. For hydrogenated nitrile butadiene rubber (HNBR)/carbon black composites, this approach quantifies a strong interaction and interphase of increased stiffness relative to the matrix (bound rubber). Macroscale mechanical tests confirm a significant increase in the mechanical stiffness for these composites. Second, we demonstrate visualization and characterization of in-situ annealing via SPM tapping-mode imaging of functionalized silica nanoparticles on polymers, as a function of temperature and time. This approach facilitates our quantification of the particle-polymer interaction and potential interphase formation at temperatures up to 150oC, and our results demonstrate a facile means by which to monitor the particle-polymer interaction during the nanocomposites formation. These SPM-enabled studies also show that particle-polymer interactions can be tailored not only by functionalizing the particle surfaces, but also by choosing subtle modifications to the composition of the polymer matrices.
12:15 PM - OO9.4
Elastic Modulus of low-k Dielectric Films Measured by Contact-resonance Frequency Versus Force Spectroscopy.
Gheorghe Stan 1 , Sean King 2 , Robert Cook 1
1 Ceramics Division, National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 2 Portland Technology Development, Intel Corporation, Hillsboro, Oregon, United States
Show AbstractOne of the challenges faced in pursuing continuous size shrinkage of nanotechnology circuitry resides in the adequate engineering of mechanical properties at the nanoscale. As an example, mechanical property control of low dielectric constant (low-k) materials is critical for fabricating robust architectures in copper interconnection-based electronics. To address such needs, we propose a novel dynamic procedure for measuring the elastic modulus of compliant thin films based on a contact-resonance versus force spectroscopy. In this procedure, correlated force and contact-resonance versus displacement responses have been resolved using force-dependent contact-resonance atomic force microscopy (AFM). The deflection and resonance frequency shift of an AFM cantilever-probe were recorded simultaneously as the probe was gradually brought in and out of contact. As the measurements were performed in the range of small applied forces, contact models that include the contribution of adhesive contact forces were considered in interpreting the measured force dependence of the contact stiffness. The technique is generally applicable for measuring the elastic modulus of thin and compliant films, in addition to thick and stiff films. We have tested the applicability of the proposed method by performing force-dependent contact-resonance AFM measurements on low-k materials for which elastic moduli were in the range of GPa to hundreds of GPa [1]. Over this elastic modulus range, the reliability of load-dependent contact AFM measurements was confirmed by comparing these results with that from picosecond laser acoustics and nanoindentation measurements.[1] G. Stan, S. W. King, and R. F. Cook, J. Mater. Res., in press (2009).
12:30 PM - OO9.5
Nanoscale Subsurface Metrology with GHz Ultrasound AFM System.
Shuiqing Hu 1 , Onara Guclu 1 , Walter Arnold 1 , Chanmin Su 1
1 , Veeco Instruments, Santa Barbara, California, United States
Show AbstractThe need for nanoscale sub-surface metrology directly impacts industries at the forefront of nano-fabrication, such as the semiconductor manufacturers and producers of advanced composite materials.In order to achieve nanometer scale resolution one needs to push to the limit of acoustic wavelength and takes advantage of near field detection at the same time. Atomic force microscopy is an idea tool for near field acoustic detection but fall far short of detection bandwidth of GHz ultrasound. A technique called self-mixing is developed to convert the GHz ultrasound into MHz bandwidth beat signal detectable by AFM cantilever system. By tuning tip surface interaction into an optimum control point, signal to noise ratio of the beat signal can reach 53 dB. Reference feature of various resolution was fabricated with buried depth of 200 nm and imaged using the GHz ultrasonic AFM. At current level of development, the line resolution is about 10 nm. Further development will facilitate the process of extracting depth information to create 3D tomography of nanometer scale sub-surface features.
12:45 PM - OO9.6
The Fracture Behavior of Nanostructures.
Andre Kaufmann 1 2 , Helmut Schift 1 , Ernst Meyer 2 , Thomas Jung 1 2
1 Laboratory for Micro and Nanotechnology, Paul Scherrer Institute, Villigen Switzerland, 2 Department of Physics, University of Basel, Basel Switzerland
Show AbstractFracture in materials is crucially determined by structural features on the nanometer scale such as cavities, occlusions, cracks, and on the atomic scale such as interstitials, substitution defects and vacancies. In this work, fracture mechanics experiments are performed with fabricated nanostructures (so-called nanotowers/nanopillars). Further-more, well defined material interfaces have been introduced into the pillars in order to act as well defined breaking points. By exerting defined forces on these structures, the adhesion strength of these specific interfaces can be studied:One way to perform such experiments is by using a Scanning Force Microscope (SFM). Here, force and topography investigations using a cantilever tip as a tool reveal infor-mation about the mechanical strength of a particular interface as well as general infor-mation about the fracture behavior of nanometer sized structures. The experiments are carried out using the contact or the tapping mode (intermitted mode) of the SFM with single nanopillars or with an ensemble of them. For statistical examinations, an area of nanopillars is scanned with an elevated force followed by an inspection scan to count the number of broken towers. This technique offers the possibility to study fatigue proc-esses under constant resp. alternating conditions in terms of the applied force, envi-ronmental conditions (liquid or air), pH, humidity, etc.Due to the small pillar dimensions, slow processes such as the weakening of the inter-face by fatigue or physical-chemical processes (corrosion) can be monitored on a con-siderably shorter time scale and under better controlled conditions. Thus, such experi-ments are less time and cost intensive as with large, real world samples in conventional fracture mechanic experiments.One application of this method is the study of the metal/polyimide interface, which is important for flexible and bendable microelectronic devices. Interface problems, namely failures after temperature and/or mechanical bending cycles have been associated to interfacial water. Hence, in a well chosen model experiment under ultra high vacuum (UHV) conditions, a precise amount of water is dosed on an in-situ produced polyimide sample and is then coated with a metal by evaporation. Afterwards, the nanopillar structures are generated by Focused Ion Beam (FIB) milling. In our presentation we demonstrate the fabrication and show first results on nanopillars breaking.This new approach provides a route towards the better understanding of fracture proc-esses down to the atomic and molecular scale. It should also be possible to receive in-formation about the plastic and elastic properties of matter and therefore be a supple-ment or even replacement for indentation experiments. Furthermore, an array of such towers can be used as a so-called WORM (Write Once, Read Many times) data stor-age device by selective fracture of individual pillars.
OO10: Kelvin Probe Force Microscopy
Session Chairs
Wednesday PM, December 02, 2009
Room 209 (Hynes)
2:30 PM - OO10.1
Kelvin Probe Force Microscopy in Application to Organic Thin Films and Lipid Monolayers.
Brad Moores 1 , Francis Hane 2 , Lukas Eng 3 1 , Zoya Leonenko 1 2
1 Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada, 2 Biology, University of Waterloo, Waterloo, Ontario, Canada, 3 Institute of Applied Photophysics , Technical University Dresden, Dresden Germany
Show AbstractWe applied Kelvin probe force microscopy (KPFM) to visualize the morphology and surface potential distribution in thiol self-assembled monolayers and lipid-protein films of lung surfactant. We have shown earlier (Leonenko et al. Biophys J. 2007) that that function of Bovine Lipid Extract Surfactant (BLES) is related to the specific molecular architecture of surfactant films. Defined molecular arrangement of the lipids and proteins of the surfactant film give rise to a local highly variable electrical surface potential of the interface. We compared the resolution of frequency modulation (FM-KPFM), amplitude modulation (AM-KPFM) and hover (HM-KPFM). At larger scale and larger surface potential deviations all modes give high resolution. At smaller scans and smaller differences in surface potential FM-KPFM mode gives more superior resolution, and therefore is preferable for imaging lipid- and lipid-protein films.
2:45 PM - OO10.2
Scanning Kelvin Probe Force Microscopy Investigations on Barrier Properties of Organic Films on Patterned Zinc Oxide Nanorod Films.
Ozlem Ozcan 1 , Berkem Ozkaya 2 , Agata Pomorska 1 , Guido Grundmeier 1
1 Technical and Macromolecular Chemistry, University of Paderborn, Paderborn Germany, 2 Interface and Surface Chemistry, Max Planck Institut für Eisenforschung, Düsseldorf Germany
Show AbstractThe synthesis of zinc oxide nanostructures have been intensively studied for applications in fields of catalysis, photoelectronics and sensors. Recently we have been able to grow ZnO nanorod films on metal/metal oxide substrates as a model system for investigating the adsorption mechanisms of organofunctional adhesion promoters. For a realistic evaluation of the adhesion properties and corrosion resistance of such a system by means of in-situ measurements it is necessary to have the untreated reference on the same sample. The reference and the nanorod coated regions must have comparable and well defined dimensions and have to be distributed in a structured manner on the substrate. The most intelligent way to obtain a film which can fulfil these criteria is to use the micro-contact printing (μ-CP) technique, where a stamp with the desired pattern is covered with the molecules of interest to be transferred to the substrate by controlled pressing.
In this paper we have prepared patterned ZnO nanorod films on various metal/metal oxide substrates by means of μ-CP with thiols and organophosphonates having carboxyl or amino end-groups. The nanorod growth was blocked or hindered on the functionalized domains and well defined, reproducible patterned surfaces have been obtained. The morphology and crystallinity of the micro-structured films were examined using scanning electron microscopy (SEM) and X-Ray diffraction (XRD). Energy-dispersive X-Ray Analysis and Raman Microscopy were performed to obtain elemental maps and chemical information. The films were then treated with adhesion promoters and organic coatings for in-situ atomic force microscopy (AFM) measurements in the Scanning Kelvin Probe Force Microscopy (SKP-FM) mode. SKP-FM is a technique where surface potential of the sample is measured in addition to the sample topography. Atmospheres with controlled humidity and traditional wet defects were applied to the patterned samples and the changes in the surface potential were monitored as a function of time at the reference and nanorod coated regions.
In combination with the utilization of a patterned surface, SKP-FM has shown very promising results as a tool in evaluation of barrier properties of organic coatings on metal / metal oxide surfaces at the micron scale leading to a better understanding of corrosion processes.
3:00 PM - OO10.3
Kelvin Probe Force Microscopy Investigation of Charge Transfer Mechanisms from Doped Silicon Nanocrystals.
Lukasz Borowik 1 , Koku Kusiaku 1 , Didier Theron 1 , Diesinger Heinrich 1 , Dominique Deresmes 1 , Thierry Melin 1 , Thuat Nguyen-Tran 2 , Pere Roca i Cabarrocas 2
1 , IEMN-CNRS, Villenveuve d'Ascq France, 2 , LPICM-CNRS, Palaiseau France
Show AbstractThe introduction of impurities in semiconductor nanocrystals is of fundamental interest to control their optical, electrical and magnetic properties[1]. Doping is essential to basically enhance electrical conductivity, and to build functional devices. This issue becomes of prime interest at the nanoscale for e.g. self-assembled devices based on organic, molecular or inorganic nanostructures, for which the control of doping can be either technologically difficult during the synthesis, and strongly depend on the environment, as in the case of carbon nanotubes[2] or physically limited, as in the case of silicon nanowires for which internal doping becomes unefficient due to dielectric screening[3].In this presentation, we investigate using ultra-high vacuum non-contact atomic force microscopy and Kelvin probe force microscopy (KFM) the possibility of using doped nanocrystals as electron sources to perform external remote doping of nanostructures and nanodevices. The focus is here to study the mechanisms of charge transfer from nanocrystals at the scale of the individual nanocrystals. To do so, we study the charge transfer from hydrogen-passivated phosphorus-doped[4] silicon nanocrystals towards silicon substrates by means of amplitude-modulation KFM. From the measurement of the electrostatic potential of ionized nanocrystals, we demonstrate that the nanocrystal doping (i) provides an internal passivation of the nanocrystal surface states and (ii) induces a charge transfer following an energy compensation mechanism similar to remote doping, but strongly enhanced by quantum confinement. Results provide a direct measurement of the nanocrystal band-gap opening induced by quantum confinement in the 2-50nm range[5], in agreement with parametrized tight-binding calculations. They also put forward the possibility of using doped nanocrystals to achieve controlled external remote doping of nanostructures and nanodevices, with expected two-dimensional charge densities in the range of 10^11-10^14 cm-2, or linear charge densities in the range of 10^5-10^7 cm-1.References: [1] For a recent review, see: D.J. Norris, A. L. Efros, S. C. Erwin, Science 319,776-1779 (2008) ; S. C. Erwin, L. Zu, M. I. Haftel, A. L. Efros, T. A. Kennedy, and D. J. Norris, Nature 36,91 (2005).; D. Yu, C.J. Wang, and P. Guyot-Sionnest, Science 300, 1277 (2003).[2] V. Derycke, R. Martel, J. Appenzeller, and Ph. Avouris, Appl. Phys. Lett. 80, 2773 (2002).[3] M. T. Bjork, H. Schmid, J. Knoch, H. Riel, W. Riess, Nature Nanotechnology 4, 103-107 (2009); M. Diarra, Y. M. Niquet, C. Delerue, and G. Allan, Phys. Rev. B 75, 045301 (2007).[4] A. R. Stegner, R. N. Pereira, K. Klein, R. Lechner, R. Dietmueller, M. S. Brandt, M. Stutzmann and H. Wiggers, Phys. Rev. Lett. 100, 026803 (2008).[5] L. Borowik, K. Kusiaku, D. Théron, D. Deresmes, H. Diesinger, T. Mélin, T. Nguyen-Tran, P. Roca i Cabarrocas (submitted to Phys. Rev. Lett.)
3:15 PM - OO10.4
Evidence of Space Charge Regions within III-V Semiconductor Nanowires.
Angela Narvaez 1 , Thalita Chiaramonte 1 , Klaus Vicaro 1 , Joao Clerici 1 , Monica Cotta 1
1 IFGW, Universidade Estadual de Campinas, Campinas, SP, Brazil
Show AbstractQuasi-one-dimensional systems such as semiconductor nanowires (NWs) are considered as one of the main possible building blocks for nanoscale electronic and optoelectronic devices. From the possible choices of materials, InP and InAs NWs have been extensively investigated due to their large carrier mobilities and small surface recombination rates. Recent works evaluating possible nanoelectronics devices, however, have shown that the electrostactic characteristics of these nano-objects still need to be addressed.In this work the electrostatic characteristics of InP and InAs NWs were investigated with spatial resolution by Kelvin Probe Force Microscopy (KPFM). This technique can provide information on the charge distribution and electronic structure of nano-objects. KPFM images - with spatial resolution as low as 10nm - show a variation of surface potential (SP) along individual NW’s and a dependence on NW diameter which is attributed to tip-sample size effects and to the increasing surface to volume ratio at the thinner regions of the NW due to tapering. This latter effect can cause charge transfer and carrier depleted regions along the NW. Heterostructured InP NWs, with lower tapering and an InAs segment inserted into the NW mid-section, were also measured. This NW structure was designed in order to minimize tip-size effects and charge transfer. In this case, changes in SP values reflect the different materials and the presence of the nanoparticle (NP) used to catalyze the growth, with no strong dependence on NW diameter. However, a space charge region can still be observed near the NW apex. These results suggest there is an effective ‘electrical contact’ formed at the NW tip due to the presence of the metallic NP and the formation of a very thin InAsP segment close to the NW/NP interface during sample cool down.
3:30 PM - OO10.5
Relaxation Behavior of Trapped Charges in Si/Oxide/Nitride/Oxide/Si (SONOS) Memory Devices by Temperature-Variable Kelvin Probe Force Microscopy.
Wonsup Choi 1 , Hyunjun Yoo 1 , Changdeuck Bae 2 , Jooho Moon 2 , Jang-Sik Lee 3 , Hyunjung Shin 1
1 National Research Lab. for Nanotubular Structures of Oxides, Center for Materials and Processes of Self-Assembly, and School of Advanced Materials Engineering, Kookmin University, Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Yonsei University, Seoul Korea (the Republic of), 3 Center for Materials and Processes of Self-Assembly, and School of Advanced Materials Engineering, Kookmin University, Seoul Korea (the Republic of)
Show AbstractPoly-Si/oxide (blocking oxide)/nitride/oxide (tunneling oxide)/silicon (SONOS) devices are one of the promising nonvolatile memory family due to the low-voltage operation, scaling capability, and high endurance. The nitride layer (Si3N4) is the key element and serves as a storage layer in the operation of memory devices. When scaled down, in particular, the characterization of the trapped charge distribution and its decay behavior according to the time at the nanometer resolution is crucial at both technological and scientific point of views. We employed the technique of variable-temperature Kelvin probe force microscopy (KPFM) to study the trapping behavior of charge carriers (both electrons and holes) in ultrathin nitride/oxide (tunneling oxide)/silicon (NOS) structures. The contact potential difference induced by electrons or holes trapped in the nitride layer can be directly measured by KPFM under high-vacuum conditions (~10-7 torr). In addition, we were able to show the spatial distribution dynamics of trapped charges by measuring the relaxation behavior at the elevated temperatures of 150–350°C, with the samples of different growth conditions and dielectric-stack structures. Previous studies have shown that the trapped charges were predominantly de-trapped by decay process, not by lateral diffusion. We have measured and characterized the phenomena of both decay and diffusion of trapped charges NOS structures, which have never been determined simultaneously. The activation energy on our NOS structures was related to be responsible for both decay and diffusion phenomena for each charge, which has been estimated by solving the Arrhenius equation. We obtained the charge retention characteristics in the temperature ranges of 150-350°C, and the activation energy for electrons and holes were, respectively, determined to be about 1.21 and 1.20 eV. The data retention time for commercial nonvolatile memories is typically guaranteed for ten years at the temperature range of 0-85°C. We have calculated that both negative and positive charges trapped have the retention time of about 22 years at 85°C. The present results and methods have a potential to be utilized to obtain the relaxation behavior of trapped charges on such memory devices.
OO11: Novel Methods
Session Chairs
Wednesday PM, December 02, 2009
Room 209 (Hynes)
4:15 PM - OO11.1
Qplus: NC-AFM with Atomic Resolution in a Temperature Range Between 5 K and 1083K.
Andreas Bettac 1 , Juergen Koeble 1 , Markus Maier 1 , Konrad Winkler 1 , Albrecht Feltz 1
1 , Omicron Nanotechnology, Taunusstein Germany
Show AbstractThe QPlus sensor with its high spring constant and an optimized quality factor allows operation at very small oscillation amplitudes and is therefore ideal for atomically resolved imaging on all types of surfaces, i.e. for insulators, semiconductors and also for metallic surfaces. We present atomic resolution imaging on a reconstructed Si(111) 7x7 in a temperature range between 50 K and 1083 K. The results demonstrate the capability of the QPlus sensor for atomic resolution in pure NC-AFM and dynamic STM measurements. At low temperatures, atomically resolved images of the rest atom layer will be presented. High temperature measurements close to the phase transition between the (1x1) and (7x7) show dynamics in the formation of step edges and kinks. Further we present atomic resolution imaging on single crystal NaCl(100) with oscillation amplitudes below 100 pm (peak to peak) and operation at higher flexural modes at frequencies of up to 318 kHz in constant Δf imaging feedback at 5K. We also present atomic resolution measurements on metallic Au(111) and Ag(111) surfaces with an extremely high stability at 5 K [1].In addition, we present first results on NC-AFM based (Δf feedback) manipulation of molecules on insulating single crystal NaCl(100).[1]A. Bettac, J. Koeble, K. Winkler, B. Uder, M. Maier, and A. Feltz, Nanotechnology 20 (2009) 264009.
4:30 PM - OO11.2
Visualization of Subsurface Structures by Heterodyne Force Microscopy.
Kuniko Kimura 1
1 Electronic science and Engineering, Kyoto University, Kyoto Japan
Show AbstractKuniko Kimura 1), Kei Kobayashi 2), Hirofumi Yamada 1), Kazumi Matsushige 1)1)Dept. Electric Science and Engineering, Kyoto Univ., 2)Innovative Collaboration Center, Kyoto Univ.Visualization technique at nanometer-scale resolution for subsurface structures of samples is essentially important for various scientific studies. It enables us to detect nanometer-scale defects in integrated circuit devices as well as to visualize in-vivo structural changes inside living cells. Heterodyne force microscopy (HFM)[1] is one of the useful techniques for visualization of subsurface structures based on atomic force microscopy (AFM). In this technique the AFM cantilever tip and the sample are vibrated at different frequencies, respectively. When the tip is in contact with the sample, a tip vibration at the difference frequency is produced due to a nonlinear tip-surface interaction. The amplitude and/or the phase of this vibration are recorded as a function of the two-dimensional tip position. In fact images of a living cell obtained by this technique were recently reported [2]. Here, we investigate the variation of the spatial resolution in the HFM images depending on the distance from the surface. We first prepared 125 um-thick polyimid film having Au particles with a diameter of 40 nm on the surface by depositing gold colloids. After drying it, a polymer solution (Shipley S1813) was spin-coated to cover the surface (coating layer). The sample was glued on a piezoelectric oscillator fixed on the AFM tube scanner. Then the cantilever tip (0.2 N/m) was contacted in the sample surface. In this setup we vibrated the sample and the tip at 800 kHz (f1) and 864 kHz (f2), respectively, such that the difference frequency (f2-f1) was equated to the contact resonance frequency of the tip. The tip vibration at f2-f1 was detected by a lock-in amplifier and imaged (heterodyne images). We successfully visualized the Au particles under the polymer film clearly by HFM. Although the Au particles were not recognized in the topograph, they were clearly visualized in the heterodyne images for the samples with the coating layer thickness of 100 - 500 nm. Even for the sample with a 900 nm-thick coating layer the Au particles were detected in the heterodyne images. We also checked the imaging capability of force modulation microscopy (FMM) working in a high frequency range. In this measurement only the sample was vibrated at 800 kHz and the tip vibration at the same frequency was detected. The results showed, however, that the Au particles could not be visualized for the samples with a coating layer thicker than 300 nm. Thus, HFM is a superior technique for the visualization of subsurface structures. In this presentation the understanding of the imaging contrast in HFM will be also discussed.[1] M.T. Cuberes et.al, J. Phys. D., 33, p2347 (2000). [2] L. Tetard et.al, Nature Nanotech., 3, p501 (2008).
4:45 PM - OO11.3
Module to Combine Microscopic Probe, Sample and Environmental Effects in Virtual AFM.
Baoxiang Shan 1 , Assimina Pelegri 1
1 Mechanical and Aerospace Engineering, Rutgers, the State University of New Jersey, New Brunswick, New Jersey, United States
Show AbstractAFM procedures have been successfully simulated using commercial programming software like Matlab, Matlab Simulink or specialized packages like Virtual Environment for Dynamic AFM (VEDA) and Self Consistent Image Force Interaction + virtual AFM machine (SciFi). Although the necessary electronic modules like automatic distance control (ADC), automatic gain control (AGC) and phase-lock loop (PPL) are easily represented by modular blocks in virtual AFM diagrams, the continuous cantilever with tip and tip-sample interactions are currently difficult to be modularized by the same means. This is due to the intrinsic complexity in describing the dynamic and multiple physical interactions involved, as well as simulating the variety of AFM working environments like liquids, biological solutions, ambient and noisy conditions. The spring-mass model of microscopic probe and equational description of tip-sample interactions could be inaccurate, and limit the depiction of novel AFM operational modes like multi-frequency excitation and frequency modulation. 3D detailed dynamic analysis of AFM probe and comprehensive tip-sample interactions using traditional finite element (FE) methods are time-consuming and non-interactive, so that they cannot be directly integrated into virtual AFM systems. Based on an interactive open system concept we have developed a Physically Equivalent Modeling (PEM) technique for high-fidelity dynamic analysis of complex physical and biological systems, by incorporating 3D object geometry, modal analysis, state space representation and model order reduction into a FE framework. Using PEM computational methodology, a 3D microscopic cantilever with tip together with a 3D atomic sample and their interactions are modeled in Abaqus. User-defined subroutines of Abaqus are programmed in C++ to formulate state space representation and perform model order reduction on comprehensive 3D AFM probe and sample system, after modal analysis of the system in Abaqus. Upon completion an effective and equivalent module of AFM probe and sample system will be constructed with the following characteristics: a) accuracy in a wide range of frequencies (a 0.5% relative error between original and reduced models was achieved in terms of the norm of their transfer functions in our example of biological tissue dynamics), b) interactivity with input and output channels, c) efficiency with few degree of freedoms (five in a above-mentioned biological example), d) extensibility to include various environmental effects, and e) interconnectibility to other modules and systems. Thus, the probe-sample module will extend the capability of virtual AFM, develop new operational modes with improved resolution, and widen its application possibilities.
5:00 PM - OO11.4
Sinusoidal Scanning for High Speed Scanning Probe Microscopy.
Sungjun Lee 1 2 , Nicholas Polomoff 1 , James Bosse 1 , Bryan Huey 1
1 Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Physical Metrology Division, Korea Research Institute of Standards and Science, Daejeon Korea (the Republic of)
Show AbstractSeveral recent advances in scanning probe microscopy have increased image speeds from minutes per frame to frames per second. High Speed Surface Property Mapping implements a combination of acoustics and Atomic Force Microscopy for amplitude and phase imaging, providing material contrast akin to standard speed intermittent-contact AFM variations. This can even be achieved with legacy systems, though several challenges must be overcome including system and especially scanner resonances. One solution employs sinusoidal instead of triangular scanner signals, substantially extending imaging speeds for high quality SPM results by minimizing resonant scanner excitation. Images of a single region acquired at line rates from 1 Hz to several kHz, with up to 20 frames per second, are presented revealing the negligible influence of sinusoidal scanning. This enables novel measurements of dynamic surface properties, as demonstrated by high speed movies quantifying in-situ domain switching in ferroelectric thin films.
5:15 PM - OO11.5
Drift and Spatial Distortion Elimination in Atomic ForceMicroscopy Images by the Digital Image CorrelationTechnique.
Zhi-Hui Xu 1 , Xiaodong Li 1 , Michael Sutton 1 , Ning Li 1
1 Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina, United States
Show AbstractThe characterization of nanomaterials and nanostructures on the nanoscale has been a tremendous challenge for many existing testing and measurement techniques. With the rapid development of microfabrication and nanofabrication technologies, appropriate and accurate tools for nanometrology and nanomechanical testing must be developed. In this study, a recently developed methodology for scanning electron microscopy (SEM) image correction has been successfully adapted to correct the drift and spatial distortion of atomic force microscopy (AFM) images. Using this approach with a standard AFM sample stage, the errors in AFM images, artificial strains for zero deformation, have been tremendously reduced. When using a sample stage with closed-loop control, the method also reduces errors, confirming that the SEM-based approach is capable of removing much of the distortion present in typical AFM images.
5:30 PM - OO11.6
Imaging of Alkane Monolayers Using AFM with High Resonance Frequency Scanner Operating in AM Mode.
Sergey Saunin 1 , Sergey Bashkirov 1 , Alexey Belyaev 1 , Dmitry Evplov 1 , Vasily Gavrilyuk 1 , Vladimir Ivanov 1 , Andrey Krayev 1 , Mikhail Savvateev 1 , Alexey Temiryazev 1 , Vladimir Zhizhimontov 1
1 , AIST-NT Inc., Novato, California, United States
Show AbstractImaging of molecular monolayers was considered as a challenging task for AFM. Most of the data on the structure of molecular layers published so far have been obtained with STM. Using advanced AFM with a high eigenfrequency scanner made it possible performing routine analysis of the alkane layers on HOPG with near-molecular resolution using conventional AM technique. Due to the significantly smaller forces exherted on the sample by AFM tip compared to STM, it is possible to investigate the structure of multiple layers and observe the rearrangement of the molecules within the layers.Examples of AFM analysis in ambient conditions of alkane layers on HOPG including the multiple layers of linear alkanes, layers formed from mixed solutions of C24H50-C36H74 and C18H38-C24H50, and monolayer islands of dodecyldiamine will be demonstrated. It will be shown that molecules of different types segregate on the surface forming either stacked layers or interpenetrating structures. Importance of the mechanical properties of the AFM's scanner for fast reaction time and low lateral drifts as well as the probe's shape for high resolution imaging will be discussed. Routs of further improvement of the control of the AFM tip-Sample interaction and lateral resolution will be discussed.
5:45 PM - OO11.7
Tip Induced Nanoscale Synthesis of Solid State Materials.
Marco Rolandi 1 , Jessica Torrey 1 , Stephanie Vasko 2 1 , Peter Morse 1 3
1 Materials Science and Engineering, University of Washington, Seattle, Washington, United States, 2 Chemistry, University of Washington, Seattle, Washington, United States, 3 Physics, University of Washington, Seattle, Washington, United States
Show AbstractDuring the ongoing quest for device miniaturization, the atomic force microscope (AFM) has risen as a promising tool for patterning nanostructures. The AFM tip is used to define a unique nanoscale environment on the sample where highly localized chemical reactions occur. This localization effect is exploited to afford the nanoscale synthesis of a broad variety of solid-state materials. In brief, a biased AFM tip traces desired patterns across a silicon substrate while immersed in a liquid precursor. The high electric field (ca. 10^9 V/m) induced in the small gap between the tip and the surface causes the precursor to react and grow nanowires that are as narrow as the tip radius. Nanowire materials include inorganic semiconductors, dielectrics, as well as diamond-like, and graphite-like carbon. The chemical and structural properties of the features are elucidated using time-of-flight secondary ion mass spectroscopy, x-ray photoemission electron microscopy, and cross sectional transmission electron microscopy. This strategy merges lithography and synthesis in a single-step and affords the precise positioning of nanocomponents for facile device integration. Potential applications include computing and sensing.