Symposium Organizers
Philippe Bergonzo CEA-LIST
Commissariat Energie Atomique (CEA/Saclay)
James E. Butler (Retired from Naval Research Laboratory)
Christoph E. Nebel Fraunhofer Institut fuer Angewandte Festkoerperphysik
Andrew T. S. Wee National University of Singapore
Milos Nesladek Hasselt University & IMEC vzw
A5: Poster Session: Diamond Electronics and Bioelectronics
Session Chairs
Monday PM, November 29, 2010
Exhibition Hall D (Hynes)
1:00 AM -
A5.27 Transferred to A11.5
1:00 AM -
A5.34 Transferred to A13.2
A1: Novel Imaging Approaches with Single Photon Sources
Session Chairs
Monday AM, November 29, 2010
Room 306 (Hynes)
9:30 AM - **A1.1
Nanoscopy With Focused Light.
Stefan Hell 1
1 Dept. of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Göttingen Germany
Show AbstractIt has been generally accepted that the resolution of a lens-based optical microscope is limited to about > 200 nm in the focal plane and > 500 nm along the optic axis, with NA denoting the numerical aperture of the lens and the wavelength of light. The discovery in the 1990’s that elementary transitions between the states of a fluorophore can be used to eliminate the limiting role of diffraction has led to light microscopy concepts with resolution on the nanometer scale. Currently, all existing and successfully applied nanoscopy methods share a common enabling element: they switch fluorescence on or off, so that adjacent features are registered sequentially in time.For example, in a typical Stimulated Emission Depletion (STED) microscope, the fluorophores are switched off (=kept dark) by overlapping the excitation beam with a de-exciting (STED) beam which effectively confines the fluorophores to the ground state everywhere in the focal region except at a tiny area where the STED beam is close to zero. Fluorophores that are located in this subdiffraction-sized smaller area are registered. Scanning the beams further in space registers those fluorophores that had been switched off. An image of the whole object is assembled by sequential registration. The resolution is now given by the smaller diameter d of this area in which the fluorophores are still fluorescent. I is the intensity of the STED beam, which, for I >> Is, entails d→0, meaning that the resolution is conceptually no longer limited by lamda.STED microscopy has been used to investigate the fate of synaptic vesicle proteins after exocytosis, thus demonstrating the potential of emerging ‘fluorescence nanoscopy’ for the life sciences. A video-rate STED microscope was used to describe the mobility of vesicles inside the axons of cultured living neurons. Live-cell STED microscopy has also been used to image activity-dependent morphological plasticity of dendritic spines, while in another study, it revealed that single sphingolipids, but not phospholipids, are transiently (< 10 ms) and locally (< 20 nm) trapped in a living cell membrane, mediated by cholesterol.The concept of STED microscopy has been expanded to low intensity operation by switching the fluorophore to a long-lived dark (triplet) state or between a ‘fluorescence activated’ and a ‘deactivated’ (conformational) state as encountered in switchable fluorescent proteins. More recent but seminal nanoscopy schemes such as PALM, STORM and also GSDIM, switch the molecules individually and stochastically to a state that emits m >>1 detectable photons in a row before returning to a dark state, allowing the calculation of their position. Altogether, lens-based optical nanoscopy is an unexpected and fascinating development in the physical sciences that is poised to impact several areas of science, in particular the life sciences, in the near future.
10:00 AM - A1.2
Photoluminescent Diamond Nanoparticles for Cellular Super-resolution Imaging.
Marie-Pierre Adam 1 , Yan-Kai Tzeng 2 1 , Jacques Botsoa 1 , Orestis Faklaris 2 , Hugues Girard 3 , Geraldine Dantelle 4 , Jean-Charles Arnault 3 , Michel Simonneau 5 , Huan-Cheng Chang 2 , Francois Treussart 1
1 Laboratoire de Photonique Quantique et Moléculaire, CNRS UMR 8537, Ecole Normale Supérieure de Cachan, Cachan France, 2 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei Taiwan, 3 Diamond Sensor Laboratory, CEA-LIST, Gif-sur-Yvette France, 4 Laboratoire de la Matière Condensée, CNRS UMR 7643, Ecole Polytechnique, Palaiseau France, 5 Université Paris Descartes, INSERM U894, Centre de Psychiatrie et Neurosciences, Paris France
Show AbstractNitrogen-Vacancy (NV) color center in diamond has a perfectly stable photoluminescence in the red and near infrared spectral region.Diamond nanoparticles (size~20 nm) containing NV color centers (fluorescent NanoDiamonds, fNDs) are therefore perfectly suited for cellular and tissues imaging in this low absorption window, and for long-term tracking.We will show that fNDs are spontaneously internalized in different cell lines including primary neurons and do not induce cytotoxicity even at high concentrations.Thanks to NV center perfect photostability, fNDs are ideal for STimulated Emission Depletion Microscopy (STED) super-resolution microscopy which requires the combination of the fluorescence excitation by a usual Gaussian intensity shape beam (wavelength 532 nm) with the high power STED beam having a doughnut shaped intensity to stimulate the emission efficiently from the excited state (wavelength 735 nm). We will present preliminary observations of super-resolution imaging of fNDs in cells using cw lasers.Such super-resolution microscopy will be used in particular to image neuronal dendritic spines morphology, which disorders are associated to numerous neurodegenerative diseases.
10:15 AM - **A1.3
Imaging Magnetic Fields Using NV Centers in Diamond.
Amir Yacoby 1
1 , Harvard University, Cambridge, Massachusetts, United States
Show AbstractDetection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1 micro Tesla, and the corresponding field from a single proton is a few nano Tesla. A sensor able to detect such magnetic fields with nanometer spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electrons or nuclear spins in complex biological molecules to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory. Recently we experimentally demonstrated an approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature. Using an ultra-pure diamond sample, we achieve detection of 30 nT magnetic fields at kilohertz frequencies after 1s of averaging. In this talk I will review some of the recent advances in the development of such a scanning magnetometer.
10:45 AM - A1.4
Optical Characterization of Diamond Nanoparticles on Transparent Thin Films and Their Applications.
Jennifer Choy 1 , Osman Bakr 1 2 , Thomas Babinec 1 , Birgit Hausmann 1 , Parag Deotare 1 , Marko Loncar 1
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal Saudi Arabia
Show AbstractChemically synthesized nanoparticles, such as fluorescent dyes and colloidal quantum dots, are commonly used as nanoprobes for biological and chemical sensing applications and single photon emitters in integrated optical devices. More recently, diamond nanoparticles (DNPs) have emerged as promising candidates for these applications, owing to their excellent physical and chemical properties, which include structural stability, chemical inertness, optical transparency, biocompatibility, and surface functionalizability. Additionally, DNPs can be made optically active by the host of color centers from defects in diamond that arise either naturally or via implantation. The fluorescence from DNPs is stable at room temperature and can have wavelengths from the green to the infrared. We present results on the optical characterization of size-controlled DNPs containing the nitrogen-vacancy (NV) defect center. DNPs from commercially obtained diamond slurries have been purified and size separated using analytical ultracentrifugation, resulting in narrow size distributions of ±13nm. As demonstration of their remarkable photo- and structural stabilities in chemical sensing applications, we have subjected the DNPs to harsh chemical and physical conditions, i.e. boiling in brine, and shown that their morphology, size distribution, and luminescence remain unchanged.Meanwhile, we propose the use of DNPs containing single NV centers as ideal single photon emitters for coupling to passive optical resonators fabricated in transparent thin films such as titania. We have designed high Q/V titania nanobeam cavities (with theoretical Q ~ 10^6 and V~0.4(λ/n)^3) that operate near the zero phonon line (637 nm) of the NV fluorescence and fabricated these structures in sputtered titania, using electron beam lithography and reactive ion etching. Finally, we have studied the optical and charge transfer dynamics of various nanoparticles integrated with titania thin films, by measuring the spectra and time traces of single emitter fluorescence using confocal microscopy. In contrast to CdSe/ZnS quantum dots, which exhibit photobleaching and blinking behavior with prolonged dark states that are consistent with the transfer of charges into the lower bandgap titania host matrix, fluorescence from DNPs are stable and non-blinking.
A2: Surface Chemistry: From Diamond to Nanodiamonds
Session Chairs
Monday AM, November 29, 2010
Room 306 (Hynes)
11:30 AM - A2.1
Chemical Reactivity of Diamond Surfaces.
Phillip John 1 , Michael Anderson 1 , John Wilson 1
1 School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh United Kingdom
Show AbstractDevelopment of the next generation of diamond devices for chemical and biological sensing requires techniques for surface modification under ambient conditions. Single crystal (100) substrates have been treated with a hydrogen plasma to maximise the (100) terrace width and produce high quality surfaces. Thermal oxidation, in dry O2, yielded monolayer oxygen coverage with a high proportion of 'on-top' (>C=O)oxygen.Covalent binding of 4-trifluoromethylbenzylamine, in solution at room temperature, to the surface carbonyl group was accomplished to form the water sensitive imine bond. Reductive animation created a water stable amine functional group on the diamond (100) surface.
11:45 AM - A2.2
Surface Chemistry Control and New Routes for Fast and Stable Functionalization of Nanodiamonds.
Hugues Girard 1 , Tristan Petit 1 , Sandrine Perruchas 2 , Jean Charles Arnault 1 , Philippe Bergonzo 1
1 Diamond Sensors Laboratory, CEA LIST, Gif sur Yvette France, 2 Laboratoire de Physique de la Matière Condensée, CNRS - Ecole Polytechnique, Palaiseau France
Show AbstractFluorescent diamond nanoparticles (fNDs) carrying nitrogen-vacancy (N-V) colored centers hold great promises for biomedical applications [1]. They combine some of the outstanding properties of bulk diamond, such as the chemical resilience or the carbon surface chemistry, as well as the benefits of a fluorescent center emitting in the far-red with an ultrahigh photostability [2]. Furthermore, their low cytotoxicity is reported [3] and their mass production is now well controlled [4].The use of fNDs to label biomolecules and track their fate in-vivo or to deliver bioactive molecules implies the addition of specific functionalities to the bare fNDs. Stability in biological media, targeting or drug-release mechanisms go through a surface functionalization of the particles with, e.g. PEG chains, proteins, ionic moieties... However, after post-synthesis purifications treatments and irradiation/annealing steps to create N-V centers, fNDs surface chemistry remains highly inhomogeneous, with amorphous carbon, graphite shells and various oxidized terminations. Here we report on the chemical preparation of NDs. Methods for surface homogenization by exposures to reactive atmospheres (plasma treatments, annealings) in order to rationalize the surface chemistry are detailed. Then, new functionalization routes are proposed as efficient ways to bind bioactive molecules on these pre-treated fNDs. The surface modifications of the NDs are characterized using X-ray Photoelectron Spectroscopy, Auger electron Spectroscopy, Fourier Transformed Infra-Red Spectroscopy, Dynamic Light Scattering and Zeta Potential measurements. By our preparation and grafting methods, novel surface properties are given to NDs, such as e.g. cationic sites, self-adhesive spots, useful for biomedical applications.[1]A. M. Schrand et al., Crit. Rev. Sol. State, 34 (2009) 18[2]S.-J. Yu et al., J. Am. Chem. Soc., 127 (2005) 17604[3]V. Vaijayanthimala et al., Nanotechnol., 20 (2009) 425103[4]Y.-R. Chang et al., Nanotechnol., 3 (2008) 284
12:00 PM - A2.3
Enhanced Reactivity of Diamond Nano-particles.
Oliver Williams 1 , Jakob Hees 1 , Christoph Nebel 1
1 Micro & Nano-sensors, Fraunhofer IAF, Freiburg Germany
Show AbstractNano-diamond particles obtained from the purification of detonation products are found tightly aggregated and with a diverse array of contaminants. This aggregation is due to sp2 carbon shells which are formed during the cooling cycle of the detonation shock wave. The de-aggregation of such material is difficult and various techniques have been proposed each with their relative merits and flaws. For example, milling techniques based on zirconia beads result in significant contamination while burning in air results in substantial material loss. In this work we present a complimentary technique based on the surface shell reactivity of these particles that has none of the above drawbacks.By heating detonation nano-diamond particles in hydrogen gas at 500 °C (10 mbar, 5 hours), we are able to produce mono-disperse colloids with particle sizes between 3-4 nm. The zeta potential of these colloids changes from negative for the untreated particles to positive for the treated material. The negative zeta potential originates from acidic groups on the untreated product that are displaced by hydrogen in the treated material. The change in zeta potential and particle size demonstrates that the particle surfaces are able to react with molecular hydrogen at relatively low temperatures. This is due to the sp2 nature of the surfaces which we have confirmed with TEM and analogous experiments on carbon black. Positive zeta potentials are a common feature of hydrogenated carbon black and larger diamond particles with less sp2 do not show this effect. Thus, we conclude that the effect is based on the sp2 nature of the detonation nano-diamond surfaces.
12:15 PM - A2.4
Predicted Site Dependence of the Binding Energies of Amino and Carboxylic Acid Groups on Diamond Nanoparticles: A New Route for Multi-functionalization.
Zachary Fitzgerald 1 , Natalie Gibson 1 , Tzy-Jiun Mark Luo 1 , Olga Shenderova 2 , Donald Brenner 1
1 Material Science, North Carolina State University, Raleigh, North Carolina, United States, 2 , International Technology Center, Research Triangle Park, North Carolina, United States
Show AbstractThe facile surface chemistry of diamond nanoparticles with a variety of different functional groups has made these systems attractive for many different applications in the materials and bio-medical sciences. To better understand and predict the covalent bonding of surface species to diamond nanoparticles, we have been using a semi-empirical electronic method to calculate surface binding energies for –NH2 and -COOH groups on hydrogen terminated 4.5 nm octahedral diamond nanoparticles as a function of binding site. The calculations predict that both functional groups prefer binding at apex sites, followed by edge and then terrace sites. For the amino group, the energy difference between bonding to an apex and edge site is ~0.3 eV, while the difference between the edge and terrace site is only ~0.1 eV. The energy difference between the apex and edge sites for the carboxylic acid group is also ~0.3 eV, but the energy difference between the edge and terrace site is ~0.7 eV. The differences in binding energies between the different sites are attributed to geometric effects that reduce steric repulsion between the functional groups and surface hydrogen for the apex and edge sites compared to the terrace sites. The larger difference in binding energy between the edge and terrace sites for the carboxylic acid compared to the amino group is attributed to the larger size of the former. This prediction of a relatively large dependence of binding energy on binding site suggests very different thermal lifetimes of these sites, and the possibility of using thermal cycling in different plasma environments to create nanoparticles with spatially heterogeneous chemical activity. Results of Monte Carlo simulations intended to test this hypothesis will be presented.
12:30 PM - A2.5
Nanodiamond Polymer Composites.
Ioannis Neitzel 1 , Mary Sullivan 2 , Vadym Mochalin 1 , Giuseppe Palmese 2 , Yury Gogotsi 1
1 Materials Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 2 Chemical Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractNanodiamond powder (ND) produced by detonation on an industrial scale is an attractive nanomaterial for reinforcing polymer matrices due to its superior mechanical, thermal and chemical properties. Composite materials are widely used for industrial and consumer applications ranging from the aerospace industry to electronic and biomedical applications. Specifically, desirable mechanical properties of the composite materials in combination with low specific weight can lead to an increased performance and fuel economy, which are major issues in the modern economy. Therefore, there exists an ongoing interest in creating composites which are stronger and lighter than pure polymers or metals. A careful selection of the composite components is of importance to achieve the desired properties. Nanodiamond is an excellent candidate for reinforcing polymer matrices due to its unique properties. Combined with a variety of chemical functionalizations, made possible due to a presence of a large number of functional groups on its surface, this material can be tailored to engineer new composites with enhanced mechanical properties. In this study, ND has been incorporated into an epoxy matrix. High concentration (up to 50%) ND samples have been produced using hot pressing and tested by depth sensing indentation with a spherical diamond indenter. An increase of up to 350% in Young’s modulus has been observed as well as an increase in hardness of up to 300% percent as compared to neat epoxy. Also, scratch tests show a significant increase in wear resistance of the composite were both piled-up and the amount of removed material have been reduced by 50%. Additionally thermal conductivity of ND epoxy samples with concentration of 30wt. % or higher has been improved. Both mechanical and thermal conductivity data suggest the formation of an interconnected network of ND particles. To further improve mechanical properties at low concentrations of ND, research on surface functionalization of ND is ongoing.
12:45 PM - A2.6
Surface Electronic Properties of Nanodiamonds.
Joseph Welch 1 , Aysha Chaudhary 1 , Mose Bevilacqua 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractThe electrical properties of as deposited mono-dispersed detonation nanodiamonds(DNDs) have been studied; a resistivity of the order of 1012 Ω/sq has beendetermined, with only one significant conduction pathway being observed. The dielectric character of the DND particles is also good, with dielectric loss tangent values in the range 0.05-0.5 being recorded. These combined observations suggest DNDs behave in electrical terms similar to thin film diamond, and that electrical applications for DNDs are worthy of pursuit. Since a simple room temperature sonication process has been used for their deposition, coating a wide-range of three dimensional substrate materials will be possible. A limitation on the electrical use the mono-dispersed DNDs, at least in the untreated, as-deposited from solution form used here, is the catastrophic loss of diamond-like character at temperatures above 400C. In contrast H-terminated NDs show greater stability and strongly modified electrical characteristics. The results be discussed in terms of the surface electrical characteristics of this interesting form of diamond.
A3: Progress in CVD Diamond Growth
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
2:30 PM - **A3.1
Routes Towards Large Area, Low Pressure Nanodiamond Growth via Pulsed MW-linear Antenna Plasma-chemistry.
Michael Liehr 1 , Frantisek Fendrych 2 , Andy Taylor 2
1 , Leybold Optics GmbH, Alzenau, Siemensstrasse 88 D-63755, Germany, 2 , Institute of Physics, Academy Sciences of the Czech Republic, Praha 8 Czechia
Show AbstractCurrent experimental configurations for MW PECVD diamond growth do not allow simple up-scaling towards large areas, which is essential for microelectronic industries and other applications. Another important issue is the reduction of the substrate temperature during diamond growth to enhance the compatibility with wafer processing technologies. Such advantages are provided by MW-Linear Antenna (LA) plasma applicators, allowing a scalable concept for diamond growing plasmas. In the present work we introduce a novel construction of LA MW applicators designed for nanodiamond growth by using plasmas ranging from continuous wave (CW) to pulsed modes of high repetition rates (up to 20 kHz).Using fast pulsing provides several advantages for diamond growth. Firstly, it allows the application of high power in short pulses, leading to non-linear MW absorption and consequently a reduction of total average input power to ~ 5W/cm2 compared to ~ 20 W/cm2 for CW LA-MWs or to typically 100-200W /cm2 for resonance cavity applicators. Despite the factor of 50 power reduction, the diamond growth rate that can be obtained at 450°C is comparable to or higher than that of resonance cavity systems. Secondly, the pulsed plasma concept brings improvements in diamond quality when compared to the CW mode. The resulting diamond films, grown by pulsed plasma, show clean grain boundaries with columnar growth, i.e. resembling classical nano-crystalline diamond (NCD) films of high crystallinity. This is achieved by the use of a tailored plasma chemistry. In fact the concentration of atomic hydrogen can be sustained with sufficiently high values during the power-off periods at the right pulse frequency, while the growth rates in the off-period is significantly reduced. This allows suppression of re-nucleation during the growth and preparation of high quality NCD films with 2-5% sp2 carbon (based on Raman measurements), for layer thicknesses ranging from 30 to 300 nm. We show how diamond quality, measured by Raman spectroscopy and by ellipsometry depends on the MW pulse frequency and CH4/CO2/H2 gas ratios. The plasma conditions are monitored by OES spectroscopy and by using plasma probing to measure the electron fluxes and the electron energy distribution function. We demonstrate highly uniform diamond films grown on Si wafers with a homogeneity < 5% over an 8 inch area.
3:00 PM - A3.2
Simulations of CVD Diamond Film Growth Using a Kinetic Monte Carlo Model: Further Insights into the Diamond Growth Process.
Paul May 1 , Jeremy Harvey 1 , Neil Allan 1 , Yuri Mankelevich 2
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Skobel’tsyn Institute of Nuclear Physics, Moscow State University, Moscow Russian Federation
Show AbstractKinetic Monte Carlo (KMC) simulations of CVD diamond growth have been used to simulate 300 atomic layers of diamond growth. We have previously used this model to gain insight into the fundamental processes, including adsorption, surface migration, beta-scission and etching, that govern CVD diamond growth for a fixed set of deposition conditions. We now report new results obtained from using this model to predict the growth rates and morphology expected from gas phase conditions that experimentally give rise to single crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) films. Despite its simplicity, the KMC model predicts growth rates and surface roughness values for each of the diamond types that are consistent with experimental observations. The relative rates of surface H abstraction and hopping determine the average surface diffusion length, λ, and (in the absence of defect formation and renucleation) this is a key parameter in controlling surface morphology. When the hopping rate is more than ~100× greater than the H abstraction rate, λ becomes <2, which means that migration is limited by the lack of availability of surface radical sites, and the migrating surface species simply hop back and forth between 2 adjacent sites but do not travel far beyond their initial adsorption site. Thus, Eley-Rideal processes dominate the growth, leading to the rough surfaces seen in NCD and UNCD. Conversely, when the hopping rate <100× higher than the H abstraction rate, migration occurs over greater distances (λ > 2), leading to Langmuir-Hinshelwood processes dominating the growth producing the smoother surfaces of MCD and SCD. By extrapolation, we predict that atomically smooth surfaces over large areas should occur once migrating species can travel ~5 sites (λ = 5), which requires a gas-phase concentration ratio of [H]/[CHx] > 13400 at the growing surface. Finally, the predictions for UNCD deposition in a microwave system were found to be anomalous compared to all the other growth conditions, probably as a result of carbonaceous particulates being created in the plasma which affect the gas chemistry in unknown ways.
3:15 PM - A3.3
Effect of Substrate Dislocations on Diamond Epilayer Devices Properties.
Thu Nhi Tran Thi 1 , Julien Pernot 1 , Franck Omnes 1 , Pierre Muret 1 , Etienne Gheeraert 1 , Bruno Fernandez 1 , Etienne Bustarret 1 , Jurgen Hartwig 2 , Francois Jomard 3 , Daniel Araujo 4
1 , Institut Néel, CNRS and Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 France, 2 , European Synchrotron Radiation Facility (ESRF), 38043 Grenoble Cedex 9 France, 3 , GEMaC –CNRS Université de Versailles , BSaint-Quentin F-92195 Meudon Cedex France, 4 , Departamento de Ciencia de los Materiales e IM y QI, Universidad de Cadiz, 11510 Puerto Rea Spain
Show AbstractOne (100) Ib HPHT substrate of 3x3mm2 was selected among 30 substrates checked by different methods such as mis-orientation, optical profiling and AFM for surface quality and bi-refringence optical microscopy and X-ray topography images for bulk quality. By optimizing MPCVD growth conditions using oxygen in the gas phase, we were able to obtain a very low boron doped layer with a smooth surface. The RMS roughness was ~2nm, similar to the substrate before growth.
Different Hall bars were fabricated on different areas on the sample in order to determine the location of defects (which come from the substrate) influencing to the devices. The high hole mobility, measured by the Hall effect, is 1250cm2/Vs at 300K, close to the highest value reported. From fitting the neutrality equation, we deduce the low boron doping level to be 5×1016cm-3 and that there is a low contribution of scattered ionized impurities around room temperature due to the low compensation. Various mobility and resistivity parameters showed inhomogeneous electrical properties. The low mobility regions of the sample correlated with high dislocation density regions as measured by X-Ray topography and high band A luminescence mapping via CL. The TEM revealed more details about the types of defect as well as their density.
In the less defective regions of the same sample (as shown by XRay topography), in order to investigate the reproducibility of Schottky diodes, we fabricated a number of planar diodes. We used two different methods to fabricate diodes: the classic ring-shape performed by O2 microwave plasma with Al contacts and the more recent method performed by ozone treatment and with Au contacts. The I(V) and C(V) characteristics showed no dependence on the treatments but rather on the dislocations density. By I(V) measurements, a forward current density of 3×10-3 A/cm2 and a reverse current density of 5x10-5 A/cm2 at ±10V are observed. The doping profiles deduced from C(V) data of these diodes give the boron concentrations in the range of 3 to 5×1016 cm-3 for all the diodes, compatible with the value of 1.3×1016 cm-3 found from the bound exciton relative intensity obtained by CL measurements and 2 to 3×1016 cm-3 obtained from SIMS measurements.
All these results confirm our success in growing homoepitaxial lightly boron doped diamond layer with its interesting electrical properties. We were able to control a low boron doping level using oxygen during MPCVD. Due to this low doping level, the electrical properties of the epilayer are sensitive to non-homogeneity of defects. The effects of dislocation in the substrate and of growth defects on device properties will be discussed in particular.
3:30 PM - A3.4
Carrier lifetime, Diffusion Length and Mobility in (100) CVD Diamond Samples Pre-treated in an O2/H2-plasma.
Wim Deferme 1 , Ken Haenen 1 2 , Milos Nesladek 1 2 , Tadas Malinauskas 3 , Kestutis Jarasiunas 3
1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 2 IMEC vzw, Division IMOMEC, Diepenbeek Belgium, 3 Institute of Applied Research, Vilnius University, Vilnius Lithuania
Show AbstractGreat advances in the deposition of high-quality homoepitaxial diamond and their commercial availability make this material interesting for detector and device applications. An important aspect of the growth is the diamond quality improvement with the thickness, related to the coalescence of individual growth sectors and the suppression of the propagation of some dislocations in the initial stage of the growth. Hence, it is interesting to know how defects (intrinsic and extrinsic) related to the initial stage of the growth influence the charge carrier parameters – their mobility and lifetime.In this work, samples are first pre-treated in an O2/H2-plasma for different times influencing the occurence of defects like unepitaxial crystals, hillocks with flat top and pyramidal hillocks at the surface after growth of 100-500μm thick diamond layers [1,2]. While the surface is studied by SEM and AFM, LITG (Light Induced Transient Grating Technique) and ToF (Time-of-Flight) studies will give information on the carrier lifetime, diffusion length and mobility of the grown layers [3,4]. It is shown that after an O2/H2-plasma treatment of more than 3 hours, the incorporation of defects in the bulk of the grown diamond is largely reduced, which influences the carrier dynamics measured by LITG and ToF. Also the surface roughness and the growth rate are influenced by the O2/H2-plasma pre-treatment as is shown by SEM and AFM. [1] J. Achard, F. Silva, O. Brinza, X. Bonnin, V. Mille, R. Issaoui, M. Kasu, A. Gicquel, phys. stat. sol. (a) 206/9 (2009), 1949[2] G. Bogdan, M. Nesládek, J. D’Haen, J. Maes, V.V. Moshchalkov, K. Haenen, M. D’Olieslaeger, phys. status solidi (a) 202/11 (2005), 2066[3] T. Malinauskas, K. Jarasiunas, E. Ivakin, V. Ralchenko, A. Gontar, S. Ivakhnenko, Diamond Rel. Mater. 17 (2008), 1212[4] W. Deferme, A. Bogdan, G. Bogdan, K. Haenen, W. De Ceuninck, M. Nesládek, phys. stat. sol. (a) 204/9 (2007), 3017
A4: Carbon Structure: From Graphene to Diamondoids
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
4:15 PM - **A4.1
Electrical Properties of the Diamond-graphene Interface.
Kian Ping Loh 1 , Priscilla Kai Lian Ang 1
1 Chemistry, National University of Singapore, Singapore Singapore
Show AbstractGraphene is a metallic conductor and diamond is an insulator. The marriage of the two materials at the interface creates interesting chemistry. In this talk, i will discuss how graphene can be transfered onto nominally undoped diamond surfaces that have been pre-treated differently (eg. H-plasma treated, O-plasma, molecular wire-coupled and UV-treated), focusing on the charge transfer and field effect mobility of the graphene on the diamond. It is found that depending on the surface terminations on diamond, the residual impurities and mobility on graphene is affected. The mechanical robustness of the graphene which is transfered to diamond is enhanced signifcantly, compared to silicon, when subjected to sonochemical agitation.
4:45 PM - **A4.2
Raman Spectroscopy as a Probe of Carbon Materials.
Mildred Dresselhaus 1
1 EECS and Physics, MIT, Cambridge, Massachusetts, United States
Show AbstractRaman Spectroscopy has been used for several decades as a probe for the structure and properties of the various types of carbon materials including both sp3 diamond materials and sp2 planar carbon materials. We include here a discussion of nanostructured forms like nanodiamond, nanotubes, fullerenes, and graphene-like materials. Insights into our present knowledge of the field and open issues remaining for future work will be discussed, including views about the use of spectroscopy to gain insights into newly discovered carbon materials, their structures and common defects.
5:15 PM - A4.3
Thermal Effects on the Raman Spectra of Diamond Nanoparticles.
Marc Chaigneau 1 , Hugues Girard 2 3 , Jean-Charles Arnault 2 , Razvigor Ossikovski 1
1 Laboratory of Physics of Interfaces and Thin Films, Ecole Polytechnique, Palaiseau France, 2 Diamond Sensors Laboratory, CEA LIST, Gif-sur-Yvette France, 3 Condensed Matter Physics Laboratory, Ecole Polytechnique, Palaiseau France
Show AbstractThe Raman spectra of diamond nanoparticles (NDs) exhibit a characteristic carbon-sp3 phonon peak that is broadened and down-shifted with respect to that of bulk diamond located at 1332 cm-1. We report on the temperature effects on the Raman spectra of NDs produced either by detonation synthesis or by milling of high-pressure high-temperature (HPHT) diamond. Moreover, different mean diameters (ranging from 3 nm to 50 nm) were investigated. In particular, we show that the behaviour of the carbon-sp3 peak is more consistent with the temperature increase of NDs due to the local heating caused by the laser (at 458 nm) rather than with the phonon confinement model alone widely used for nanoparticles spectra interpretation in the literature [1-3]. Local temperatures as high as 700 K are reached as confirmed by the anti-Stokes spectra. We use a Fano-resonance model, modified to account for the nanoparticle mean size and combined with the Klemens model for the temperature effect, to fit the experimental first-order Raman spectrum. We further show that the phonon behaviour with temperature also depends on the synthesis method (detonation or HPHT) and the NDs mean size. Furthermore, the thermal behaviour of the broad Raman band in the 1500-1700 cm-1 range is likewise dependent on the synthesis method used. Eventually, the reversibility of the thermally-induced phonon shift can be used to distinguish between the presence of sp2 clusters and that of surface hydroxyl groups in the nanoparticles.[1] M. Yoshikawa, Y. Mori, M. Maegawa, G. Katagiri, H. Ishida, A. Ishitani, Appl. Phys. Lett. 62, 3114 (1993).[2] J. W. Ager III, D. K. Veirs, G. M. Rosenblatt, Phys. Review B 43, 6491 (1991).[3] K. W. Sun, J. Y. Wang, T. Y. Ko, Appl. Phys. Lett. 92, 153115 (2008).
5:30 PM - A4.4
Local Stress-strain Structure at Dislocation in CVD Diamond Observed by Raman Peak-shift Mapping.
Yukako Kato 1 , Hitoshi Umezawa 1 , Hirotaka Yamaguchi 2 , Shinichi Shikata 1
1 Diamond Research Laboratory, Advanced Industrial Science and Technology (AIST), Tsukuba Japan, 2 Nanoelectronics Research Institute, Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract Diamond has attracted much attention due to the parameter for the high power device application. Because diamond has a wide band gap, high breakdown field, high thermal conductivity, it is expected to be a material using Schottky barrier diode [1, 2] as the high breakdown voltage and high temperature operation devices. For the development of that diamond device, the study on defects in respect to the device characteristics [3] is the most important topic for this consideration. However, the study covered this topic is not enough for the general discussion. In our presentation, it is shown that the raman microscopic peak-shift mapping as the experimental data of the local stress-strain at the dislocation in CVD diamond. The dislocation position is decided by the synchrotron x-ray topographies, Cross-Nicole images and Cathodoluminescence mapping. The sample is epitaxial diamond film. It was deposited on HPHT Ib(100) substrates by microwave plasma CVD method. Raman spectra and peak-shift map were recorded by using raman microscope, HR800 (Horiba Jobin-Yvon), with 633 nm excitation. From the peak-shift mapping around the dislocation, the stress-strain structure was observed. Cross-sectional peak-shift mapping at same area is shown the dislocation. Its grown direction is along <111>. Because of this observation, we suggest that this is the edge dislocation. From the luminescence mapping, it is shown that the observed dislocation and others are on one side of color zoning. This zoning is derived from the cubic or octahedral growth structure of CVD diamond.Acknowledgment:The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan financially supported this study. The x-ray topography experiment was performed under approval of the Photon Factory Advisory Committee (Proposal No. 2010G168). We thank Dr. T. Teraji(NIMS) for the measurement of CL mapping and valuable discussions.Reference:[1] “Leakage current analysis of diamond Schottky barrier diode," H. Umezawa, T. Saito, N. Tokuda, M. Ogura, S. G. Ri, H. Yoshikawa, S. Shikata, Appl. Phys. Lett. 90, 73506 (2007).[2] “Diamond low-leakage Schottky barrier diode,” H. Umezawa, K. Ikeda, N. Tatsumi, S. Shikata, Proceedings of ICSCRM 2007, We-P-81.[3] “Reduction of epitaxial defects in diamond for high power device,” N. Tatsumi, H. Umezawa, S. Shikata, Proceedings of ICSCRM 2007, Th-P-33.
5:45 PM - A4.5
Ultra-low Charge Injection Barrier in Diamondoid Molecular Electronic Devices.
Jason Fabbri 1 , Nazanin Davani 1 , Peter Schreiner 2 , Jeremy Dahl 1 , Nicholas Melosh 1
1 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States, 2 Institute of Organic Chemistry, Justus-Liebig University, Giessen Germany
Show AbstractRecently isolated higher diamondoids are 1-2 nm diamond molecules. They are in the size range where quantum confinement effects are expected to occur and they can be easily assembled into diamond nanoelectronic devices. We obtain the diamondoids in high purity through isolation from petroleum. Hydrogen surface passivation allows for site specific functionalization with thiols, amines, etc. Here we present transition voltage spectroscopy characterization of the electrical properties of diamondoid-thiol monolayer junctions. We find a 0.3 eV barrier for hole charge carrier injection from the gold electrode into the diamond molecules. This is the lowest value yet observed in the gold/thiol self-assembled monolayer system commonly employed in molecular electronics. Applications to light emitting diodes and electron emission devices will be discussed. We use three testing platforms to verify our result – conducting probe AFM, cross-wire junctions, and large-area lift-on junctions along with DFT simulations and ultraviolet photoelectron spectroscopy characterization. We extend the work to monolayers of diamondoid thiols on silver and diamondoid alkenes and silanes on silicon to suggest how the unique electronic properties and interactions of diamond molecules can be used to create high performance devices.
A5: Poster Session: Diamond Electronics and Bioelectronics
Session Chairs
Monday PM, November 29, 2010
Exhibition Hall D (Hynes)
9:00 PM - A5.1
Defect States in Irradiated Boron-doped Diamond Films Investigated Using Surface Photovoltage and Photoluminescence Spectroscopy.
Sanju Gupta 1 , R. Peters 2 , J. Paramo 2 , J. Farmer 3 , Y. Strzhemechny 2
1 Chemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 Physics and Astronomy, Texas Christian University, Dallas Fort Worth, Texas, United States, 3 MURR and Physics, University of Missouri, Columbia, Missouri, United States
Show AbstractReliability, quantification and qualification are the crucial issues holding back diamond as an engineering material from playing a larger role in harsh environment applications. In general, diamond is known for being more radiation-hard than common mature semiconductors (e.g. Si, GaAs and AlGaN). For applications such as deep UV photodiode (alternatively, visible blind), medical radiotherapy and novel nuclear micro-battery, it is critical to demonstrate material’s structural integrity and physical stability. The present work is driven by our recent reports [Gupta et al. J. Mater. Res. 24 (2009); ibid. 25 (2010)], where we carried out detailed investigations on the effects of boron doping and gamma irradiation on boron-doped diamond (BDD) films grown by microwave plasma-assisted chemical vapor deposition. We demonstrated the role of point defects induced by gamma irradiation in BDD films (grown with [B]/[C]gas = 4000 ppm that translates to boron concentration of > 1020 cm-3 in the films), which transforms the quasi-metallic to semiconducting nature facilitated by passivation of electrically active boron via hydrogen migration. Though boron as an impurity brings a complexity, it makes diamond either a lightly doped or a degenerate semiconductor depending upon the level of doping. The present work employs among others surface photovoltage (SPV) spectroscopy providing a further insight into the identification of conduction versus valence band nature of the defect-related transitions and the defect level positions within the band gap, as well as the ability to measure relatively low densities of surface states. While we did not observe any prominent spectral feature for the pristine BDD sample, there are several major spectral features for the gamma-irradiated samples. SPV sub-band-gap transitions were observed to occur at 1.2, 1.3, 1.5 eV from valence and 1.25, 1.4, 1.8 and 2.1 eV from conduction band. It is quite plausible that the transitions can be attributed to the top boron-doped diamond layer (thickness ~ 200 nm) and they refer with respect to the corresponding electronic bands in a semiconducting material. Likewise, we have also employed temperature-dependent photoluminescence spectroscopy to assess radiation-induced lattice/point defects and observed point defect GR1 center peak at 1.68 eV, B-related band at 2.3 eV and intrinsic defect (5RL center) band at 2.91 eV. These results will be discussed in light of the radiation-induced structural modification in an otherwise known radiation-tolerant diamond films for nuclear micro-battery. The author (SG) acknowledges O. Williams and K. Haenen (IMR-Belgium) and P. W. May (Bristol University, UK) for some of the BDD samples.
9:00 PM - A5.11
Detection of Melittin Induced Distruptions of Supported Lipid Bilayers on Boron Doped Nanocrystalline Diamond Film.
Vaclav Petrak 1 2 , Lars Grieten 4 , Andrew Taylor 2 , Frantisek Fendrych 2 , Miroslav Ledvina 3 , Patrick Wagner 4 , Milos Nesladek 4
1 Faculty of Biomedical Engineering, Czech Technical University, Kladno Czechia, 2 , Institute of Physisc AS CR, Prague Czechia, 4 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 3 Gilead Sciences and IOCB Research Center, Institute of Organic Chemistry and Biochemistry AS CR, v.v.i., Prague Czechia
Show AbstractSubstrate-supported lipid bilayers (SLBs) are commonly used as a model of cell membranes for biotechnological applications and scientific research. They are composed essentially of a phospholipid bilayer membrane absorbed on the surface and can serve as sensory elements for lipid-bilayer based sensors. [1]In this work, we study a self-assembly and subsequent disruption of supported lipid bilayers on a boron doped nanocrystlline diamond film (B-NCD) by impedance spectroscopy.B-NCD films were grown in a plasma enhanced chemical vapor deposition (PECVD) reactor, which allows for the deposition of films of low surface roughness. Neutral dioleoyl-phosphatidylcholine (DOPC) and negatively charged dioleoyl-phosphatidylserine/dioleoyl-phosphatidyl-choline (20% DOPS/80% DOPC) vesicles for SLB self-assembly were prepared by sonication and a SLB was formed on the the surface of B NCD via the fusion of liposomes method. Formation of a SLB was monitored by confocal fluorescence microscopy and impedance spectroscopy. Melittin and phospholipase 2 (PLA2) were used as membrane disruptive agents.Impedance spectroscopy as well as confocal microscopy confirmed succesfull formation of a SLB on the surface of B-NCD, which remained present on the surface after flushing of redundant liposome. Mellitin and PLA2 induced a change of impedance characteristic when introduced into measurement chamber. We discuss suitability of impedance spectroscopy as a tool for the investigation of the effect of Melittin and PLA2 on the SLB integrity. We further discuss biosensing properties and limitations of a lipid membrane as sensory element on B NCD.[1] E T Castellana and P S Cremer."Solid supported lipid bilayers: From biophysical studies to sensor design." Surface Science Reports. 61. (2006) 429-444.
9:00 PM - A5.12
Ionic Strength as a Driving Force of Nanodiamond Aggregation in Aqueous Solution.
Vaclav Petrak 1 2 , Petr Cigler 3 , Miroslav Ledvina 3 , Vladimira Rezacova 1 2 , Josef Masek 4 , Jaroslav Turanek 4 5 , Stoffel Janssens 6 , Ken Haenen 6 , Milos Nesladek 6 7
1 Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno Czechia, 2 Department of Functional Materials, Institute of Physisc AS CR, Praha 8 Czechia, 3 Gilead Sciences and IOCB Research Center, Institute of Organic Chemistry and Biochemistry AS CR, v.v.i., , Prague Czechia, 4 , Veterinary Research Institute, Brno Czechia, 5 , South Bohemia University, Ceske Budejovice Czechia, 6 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 7 Division IMOMEC, IMEC vzw, Diepenbeek Belgium
Show AbstractNanodiamonds (ND) have gained attention of a wide scientific audience due to their inexpensive large-scale synthesis an interesting application in biological and medical sciences for tracking, based on nitrogen-vacancy centre (NV) luminescence.In biological and medical application it is essential to prepare ND fully dispersed in aqueous solutions containing dissolved salts and ionic substances. This is especially true for application of ND as a biomarker to physiological solution where it is very important to prevent clustering.In this study we show the influence of ionic characteristics of dispersion on aggregation of ND and their corresponding ζ potential. Several types of commercially available ND particles were used in this study in native and functionalized form. Particles were deagglomerated by sonication prior diluting in aqueous solutions of various pH and ionic characteristics. The size of ND was evaluated by dynamical light scattering (DLS) and ζ potential was measured. The surface termination was controlled from H-ND to OH, O, F and other functional groups.The particles exhibited a strong tendency towards aggregation in aqueous environments outside a limited range of pH values. Aggregation of ND was also found to be occurring in the presence of ionic substances. The degree of aggregation was proportional to the ionic strength of the solution and was different for various commercial ND. The important factor controlling the agglomeration was the surface termination, influencing ζ potential and ND stability in various solutions.
9:00 PM - A5.13
Production of a High Density of NV- Centers in HPHT Type 1b Bulk Diamond.
Jacques Botsoa 1 2 , Thierry Sauvage 1 , Pierre Desgardin 1 , Elisa Leoni 1 , Francois Treussart 2 , Marie-France Barthe 1
1 Conditions Extrêmes et Matériaux : Haute Température et Irradiation, CNRS UPR 3079, Orléans France, 2 Laboratoire de Photonique Quantique et Moléculaire, UMR 8537 CNRS ENS Cachan, Cachan France
Show AbstractIn diamond, high-density ensembles of the negatively charged nitrogen-vacancy (NV-) color center in diamond is promising for applications such as ultrasensitive magnetometry which relies on the optical detection of the NV- electron spin resonance.For this purpose, the optimization and adequate control of the formation of NV- ensembles are needed. So, we have studied the optimal conditions to produce NV- ensembles by the route of proton irradiation for vacancy creation followed by annealing under vacuum of the diamond sample. Attention has particularly been paid to the influence of proton fluence on vacancy creation, as well as annealing temperature and duration. Several HPHT type 1b diamond samples from Element 6 have been irradiated with 2.4 MeV protons at fluences ranging from 1×1012 at/cm2 to 1×1017 at/cm2, annealed under vacuum at temperatures ranging from 600°C to 1000°C during times varying from 1h to 20h. Each sample has been characterized at different stages of the NV- formation process (before irradiation, after irradiation and after annealing) by Slow Positron Beam based Doppler annihilation-ray Broadening (SPBDB) spectrometry and confocal photoluminescence (PL) spectroscopy. SPBDB shows that before annealing, and at low proton fluence, the formation of monovacancy defects is observed, while at higher fluences, a new vacancy related defect appears. After annealing, SPBDB shows the formation of a new defect, identified as the NV- center also observed by PL. NV- concentration has been estimated from PL intensity, using single NV- PL intensity as the reference. Concentrations up to 14 ppm have been measured in the best samples corresponding to a N→NV conversion efficiency of about 4%. Moreover, infrared absorption measurements carried out on non-annealed samples highlight the discrepancy between vacancy concentration and Stopping and Range of Ions in Matter (SRIM) simulations. The influence of proton fluence and of annealing time and temperature will be discussed.
9:00 PM - A5.14
Nanostructured Diamond-like Carbon Films Formation by Thermionic Vacuum Arc Method.
Ana Mihaela Lungu 1 , Aurelian Marcu 1 , Ionut Jepu 1 , Corneliu Porosnicu 1 , Cristian Lungu 1 , Cristiana Grigorescu 2
1 Plasma Physics, NILPRP, Magurele-Bucharest Romania, 2 Material Characterization, INOE 2000, Magurele-Bucharest Romania
Show AbstractNanostructured diamond-like carbon films have been deposited from the pure vapor carbon plasma using an original thermionic vacuum arc method [1]. Silicon single crystalline wafers and germanium plates held at 400oC were used for substrates. The influence of the main process parameters (discharge voltage and the intensity of the tungsten filament providing the electron beam) to the films’ characteristics was investigated by different techniques such as HRTEM, SAED, XPS and Raman spectroscopy. The films consist of complex 2-10 nm nanodiamond particles embedded in an amorphous carbon matrix. XPS measurements showed more than 60% sp3 over the coexiting sp2 and sp1 chemical bonds. The Raman scattering measurements have shown characteristic D (disorder band) and G (C-C stretching in the graphite plane) modes of carbon in all samples, with a ratio of the integral intensities varying with the deposition parameters with an optimal value for samples produced with 600 eV ions. In addition to the G and D modes, a feeble Raman feature was observed in the low frequency range of the spectra, i.e. between 150 and 250 cm-1 in the samples deposited at ion energies around 800 eV. This feature was remarked in carbon nanotube-like structures and its characteristic frequency is related to the nano-dimension of the crystallites embedded in the disordered carbon phase. Protective and antireflex coatings based on the prepared films were applied on a wide range of optical components as well as on tungsten substrates in order to simulate the erosion product deposition and fuel retention after a fusion experiment campaign. [1] C. P. Lungu, I. Mustata, G. Musa, V. Zaroschi, Ana Mihaela Lungu and K. Iwasaki: Low friction silver-DLC coatings prepared by thermionic vacuum arc method, Vacuum, 76, Issues 2-3, 127-130, (2004)
9:00 PM - A5.15
Determination of Boron Concentration in Doped Diamond Films.
Shannon Demlow 1 , T. Grotjohn 1 2 , D. Reinhard 1 2 , M. Becker 2 , J. Asmussen 1 2
1 Electrical and Computer Engineering (ECE), Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractDiamond’s exceptional properties, such as a wide bandgap, high breakdown voltage, and high electron and hole mobilities, make it a potentially useful semiconductor for high-temperature and high-power devices. Boron-doped p-type diamond has applications for the fabrication of electrodes for electrochemistry and electronic devices such Schottky-barrier diodes and metal-semiconductor field effect transistors. The realization of useful devices requires the deposition of high quality, controlled conductivity films. Our previous work1,2 on the deposition of high-quality boron-doped single crystal diamond (SCD) measured the growth rates of boron-doped films as a function of the concentration of diborane and methane in the feedgas with the aim of increasing the growth rate and the quality of the films. Previous work3,4 on the characterization of the electrical properties of films utilized infrared absorption techniques and temperature dependant conductivity measurements performed using a four point probe.This work expands upon the previous effort to grow and characterize high quality boron-doped diamond films. Films are deposited on HPHT SCD substrates using a microwave plasma-assisted CVD reactor with hydrogen, methane and diborane in the feedgas mixtures. Boron-doped diamond films are grown over several orders of magnitude of boron concentrations. Experimental results obtained for electrical conductivity measured with a four-point probe, IR absorption data measured with FTIR, and boron concentration measured with SIMS are analyzed toward the aim of developing reliable calibrations for the determination of boron concentration in diamond films. Temperature dependant conductivity data is analyzed to determine dopant activation energies, and sample preparation methods such as cleaning and annealing steps are examined to determine and control surface and near surface conduction and dopant activation properties.References1. R. Ramamurti, M. Becker, T. Schuelke, T.A. Grotjohn, D. K. Reinhard and J. Asmussen, Diamond & Related Materials, Vol. 17, pp. 1320-1323, (2008)2. R. Ramamurti, M. Becker, T. Schuelke, T.A. Grotjohn, D.K. Reinhard and J. Asmussen, Diamond & Related Materials, Vol. 18, pp. 704-706, (2009)3. S.S. Nicley (S.N. Demlow), D. Tran, C. Fansler, D.K. Reinhard, T.A. Grotjohn, J. Liebich, C. Pieper, M. Becker, J. Asmussen, Presented at the New Diamond and Nano Carbons Conference, June 7-11 2009, Traverse City, MI4. T.A. Grotjohn, S.S. Nicley (S.N. Demlow), D. Tran, D.K. Reinhard, M. Becker, J. Asmussen, Conference Proceeding, 2009 MRS Fall Meeting, Boston, MA Nov 30- Dec 4 2009. Paper #: 1203-J17-17
9:00 PM - A5.16
Thermal and Electrical Conduction Properties of Nanocrystalline Diamond/Amorphous Carbon Composite Films.
Kungen Teii 1 , Tomohiro Ikeda 1
1 , Kyushu University, Kasuga, Fukuoka Japan
Show Abstract The performance of silicon-based electronic devices is more and more approaching their upper temperature limit when they are applied to high-temperature and high-power electronics, which is essential for hybrid and electric vehicles. It is necessary to radiate extra heat efficiently through a heat sink (typically made of aluminum) coated with a heat-resistant material with high thermal conductivity. Diamond has the highest thermal conductivity in all materials, which at room-temperature is more than 1000 W/mK depending on the quality. The electrical conductivity of diamond films can be varied by p- or n-type doping. However, at high temperatures, diamond films show low adhesion to aluminum substrates due to a large difference in thermal expansion coefficient between diamond and aluminum. Nanocrystalline diamond films are composed mainly of two different carbon phases: the diamond phase in form of nano-sized grains and amorphous carbon at the grain boundaries. They are typically formed under C2 dimer-rich conditions by CVD in Ar-rich/CH4 plasmas. The electrical conductivity of nanocrystalline diamond films can be varied by nitrogen addition. The remaining subject is how to control the thermal expansion coefficient while maintaining the thermal conductivity. The authors showed a way of increasing the diamond/amorphous carbon volume ratio in nanocrystalline diamond films by increasing the C2 density in microwave plasma-enhanced CVD [1]. This method is based on dissociation and recombination kinetics of hydrocarbons triggered by Ar. It is possible to control the thermal expansion coefficient by varying the diamond/amorphous ratio. In this study, we examine thermal and electrical conduction properties of nanocrystalline diamond films prepared by controlling the C2 density. The films were deposited on aluminum and silica substrates with scratching pretreatment using diamond powder. The diamond/amorphous ratio in the films increased with the C2 density. The room-temperature thermal conductivity in the films increased up to more than 20 W/mK when the diamond fraction evaluated by transmission electron microscopy was increased up to about 70%. Nitrogen incorporation in the films increased the room-temperature electrical conductivity considerably, however, the thermal conductivity decreased. This suggests that a decrease in the diamond/amorphous ratio by nitrogen addition increased the thermal resistance at the grain boundaries. Moreover, oxygen incorporation decreased both the electrical and thermal conductivities. The temperature dependence of the thermal conductivity was found to be described reasonably by the phonon-hopping model in disordered materials.[1] K. Teii and T. Ikeda, Appl. Phys. Lett. 90, 111504 (2007).
9:00 PM - A5.17
A Diamond Film-based Beta Radiation Sensor.
Javier Morales 1 5 , R. Bernal 2 , C. Cruz-Vazquez 3 , J. Almaguer 4 , V. M. Castano 5
1 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autonoma de Nuevo leon, San Nicolas de los Garza, Nuevo Leon, Mexico, 5 Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Queretaro, Queretaro, Mexico, 2 Departamento de Investigacion en Fisica, Universidad de Sonora, Hermosillo, Sonora, Mexico, 3 Departamento de Investigacion en Polimeros y Materiales, Universidad de Sonora, Hermosillo, Sonora, Mexico, 4 Facultad de Ciencias Fisico matematicas, Universidad Autonoma de Nuevo Leon, San Nicolas, Nuevo Leon, Mexico
Show AbstractDiamond films exhibits excellent properties as high heat conductivity and low electrical conductivity, due to phonon phenomena. Also, its strong valence bonds allow gap values up to 5.4 ev. When diamond films are exposed to beta radiation, some electrons pass from the valence to the conduction band, in this new energetic state the diamond properties are different, the changes in electrical properties are more significant than the thermal ones. The goal in this work is to estimate the variations of the electrical conductivity as a function of beta radiation dose and temperature, based on thermoluminescence experimental data, aiming to use diamond thin films as beta radiation sensor.
9:00 PM - A5.18
Homoepitaxial Growth of High Quality Thick Diamond Film with Microwave Plasma CVD Technique.
Hong-Xing Wang 1 , Noritaka Ishigaki 1 , Toshiki Ohkawa 1 , Shinichi Kokami 1 , Hideo Inoue 1 , Ryuuichi Terajima 1 , Katsuhiko Mutoh 1 , Toshiro Kotaki 2
1 , R&D, Diamond CVD Systems Department,Seki Technotron Corp., Tokyo, Tokyo, Japan, 2 , NJC Institute of Technology, Namiki Precision Jewel Co. Ltd., Tokyo, Tokyo, Japan
Show AbstractDiamond film collects all the outstanding properties of mechanics, electronics, heat, and optics etc. together making it have potential applications in the fields of wide range optical transparent window material, super-hard coating tools, espically, in the field of high power electron devices which can work with high frequency and in high temperature environment. This encouraged researchers to extensively investigate the synthesis techniques to develop large area single crystal diamond substrate and high quality homoepitaxial diamond film. Recently, it is reported that high quality diamond films have been grown with several range methane concentration, resulting in a device-grade diamond film, by which some devices have been developed[1,2]. However, most of these results have been achieved using microwave plasma chemical vapor deposition(MPCVD) system with an end-launch (vertical) type chamber. There are few reports about the growth of high quality diamond film by MPCVD with the over-mode (horizontal) type chamber. Also, some of the un-doped single crystal diamond growth techniques are still unclear.In this study, we report a growth of high quality thick diamond film on high pressure and high temperature diamond substrate by microwave plasma chemical vapor deposition system with the over-mode (horizontal) type chamber. First, the effect of growth parameters on the growth film morphologies was investigated, indicating that the diamond film is very sensitive to the growth temperature and input microwave power. Then, different configurations of sample holders were used in our experiment, illustrating that high quality diamond film can be grown by using the sample holder with smooth surface. Finally, the as grown samples were characterized by Raman spectroscopy, x-ray diffraction, cathodeluminescence, and photoluminescence techniques.[1] H. Okushi, H. Watanabe, S. Ri, S. Yamanaka, D. Takeuchi, J. Cryst. Growth 2002, 237-239, 1269.[2] Tokuyuki Teraji, Toshimichi Ito, J. Cryst. Growth 2004, 271, 409.
9:00 PM - A5.19
VD Diamond Dislocations Observed by X-ray Topography, Cross-nicole Image and Cathodoluminesence Mapping.
Yukako Kato 1 , Hitoshi Umezawa 1 , Hirotaka Yamaguchi 2 , Shinichi Shikata 1
1 Diamond Research Laboratory, Advanced Industrial Science and Technology (AIST), Tsukuba Japan, 2 Nanoelectronics Research Institute, Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract Diamond has attracted much attention due to the parameter for the high power device application. Because diamond has a wide band gap, high breakdown field, high thermal conductivity, it is expected to be a material using Schottky barrier diode [1, 2] as the high breakdown voltage and high temperature operation devices. For the development of that diamond device, the study on defects in respect to the device characteristics [3]