Symposium Organizers
Timothy Gessert National Renewable Energy Laboratory
Sylvain Marsillac University of Toledo
Takahiro Wada Ryukoku University
Ken Durose Durham University
Clemens Heske University of Nevada-Las Vegas
Y1: Growth and Performance of Compound Thin Film Solar Cells
Session Chairs
William Shafarman
Takahiro Wada
Tuesday PM, April 10, 2007
Room 2024 (Moscone West)
9:30 AM - **Y1.1
Challenges in Understanding Chalcopyrite Semiconductors for Photovoltaics.
Hans-Werner Schock 1
1 Solar Energy Technology, Hahn-Meitner-Institut, Berlin Germany
Show Abstract10:00 AM - **Y1.2
Progress in CIGS Solar Cell Processes and Characterization.
Shigeru Niki 1 , Syogo Ishizuka 1 , Kei-ichiro Sakura 1 , Koji Matsubara 1 , Akimasa Yamada 1 , Hitoshi Tampo 1 , Hisayuki Nakanishi 2 , Norio Terada 3
1 RCPV, AIST, Tsukuba, Ibaraki, Japan, 2 , Tokyo University of Science, Noda, Chiba, Japan, 3 , Kagoshima University, Kagoshima, Kagoshima, Japan
Show Abstract10:30 AM - Y1.3
A Novel Laser-Assisted Deposition Technique for CIGS Thin Films and Solar Cells.
Tokio Nakada 1 , Keita Nozawa 1 , Yasuyuki Ishii 1
1 Electrical Engineering and Electronics, Aoyama Gakuin University, Sagamihara Japan
Show AbstractHigh-quality Cu(In1-xGax)Se2 (CIGS) thin films are required for achieving high efficiency thin-film solar cells. This contribution presents a novel laser-assisted-deposition (LAD) technique for improving the crystallographic quality of CIGS thin films and cell performance. In LAD technique a pulse excimer laser (KrF : 248nm, 100Hz) was irradiated onto the substrate surface during CIGS deposition by three-stage process. The crystallographic properties of CIGS thin films grown by three-stage process and LAD were characterized by SEM, TEM and XRD analysis. Time-resolved photoluminescence (TRPL) measurement was also carried out in order to predict a photovoltaic potential of CIGS thin films grown by LAD. The grain size of CIGS thin films became large, and the (112) orientation was enhanced by LAD process. The CIGS deposition was stopped at each step of three-stage process to check the crystallographic properties. As a result, the (InGa)2Se3(110)orientation which leads to the (112) orientation of CIGS was enhanced by the laser irradiation at the 1st step. In contrast, almost no effect was observed when the excimer laser was irradiated at 2nd or 3rd steps. Therefore it becomes evident that the excimer laser irradiation at the first step was most effective to improve the crystalline quality of CIS thin films. TRPL measurement revealed that the PL life time increased from 33 to 45 ns by the laser irradiation during CIGS deposition. This suggests that high efficiency solar cell would be achieved by using LAD process. The solar cells with a ZnO:Al/ZnO/CIGS/Mo/SLG structure were fabricated using two types of CIGS thin films prepared by three-stage process and LAD technique. The average Ga/(In+Ga) determined by ICP (Inductively Coupled Plasma Spectroscopy) was around 0.4. It was found that the open circuit voltage (Voc), fill factor (FF) and the efficiency of the solar cells increased significantly by LAD technique. For instance, a 16.3% efficiency (with Voc=0.659 V, Jsc=34.8 mA/cm2, FF=0.709) was achieved for LAD. It contrasts well with a 14.4 % efficiency (with Voc=0.624 V, Jsc=34.7 mA/cm2, FF=0.662) for three-stage process with the same deposition conditions. This result agrees well with the TRPL data mentioned above. Further experiment was carried out for CIGS thin films with different Ga contents. It was also found that the crystalline quality of CIGS thin films and cell performance were improved by LAD process for all range of Ga content. In conclusion, we found that the LAD process is effective to improve not only crystalline quality of CIGS thin films but also the cell performance.This work was supported in part by NEDO as “R & D for Future technology of PV system”.
10:45 AM - Y1.4
A Liquid Precursor Approach to CuInSe2 Based Photovoltaics.
Jennifer Nekuda 1 2 , Maikel van Hest 2 , Calvin Curtis 2 , Alex Miedaner 2 , Ryan O'Hayre 1 , David Ginley 2
1 Metallurgy and Materials Engineering, Colorado School of Mines, Golden, Colorado, United States, 2 , National Renewable Energy Laboratory, Golden, Colorado, United States
Show AbstractTuesday, April 10Transferred Poster Y3.38 to Y1.4 @ 9:45 amA Liquid Precursor Approach to CuInSe2 Based Photovoltaics. Jennifer Ann Nekuda
11:30 AM - **Y1.5
Development of Bi-facial CdTe Solar Cells on Glass and Polymer Substrates.
Genadiy Khripunov 2 , Alessandro Romeo 3 , Hans Zogg 2 , Ayodhya Tiwari 1 2
2 Thin Film Physics Group, ETH Zurich, Zurich Switzerland, 3 Faculty of Science, University of Verona, 37134 Verona, Italy Italy, 1 Electronic and Electrical Engineering, Loughborough University, Leicestershire United Kingdom
Show AbstractTueday, April 10New Presentation Time and Paper NumberUpgraded to Invited StatusY1.4 @ 9:45 am to *Y1.5 @ 10:30 amDevelopment of Bi-facial CdTe Solar Cells on Glass and Polymer Substrates. Ayodya Nath Tiwari
12:00 PM - Y1.6
Preparation of Cu(In1-xGax)Se2 Thin Films and Solar Cells Using a Se-radical Beam Source.
Shogo Ishizuka 1 , Akimasa Yamada 1 , Hajime Shibata 1 , Keiichiro Sakurai 1 , Paul Fons 2 , Koji Matsubara 1 , Shigeru Niki 1
1 Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki Japan, 2 Center for Applied Near-Field Optics Research, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract12:15 PM - Y1.7
Temperature-dependent Degradation Modes in CdS/CdTe Devices.
David Albin 1 , Samuel Demtsu 2 , Anna Duda 1 , Wyatt Metzger 1
1 PV Devices and Electronic Materials, National Renewable Energy Laboratory, Golden, Colorado, United States, 2 , SoloPower Inc, Milipitas, California, United States
Show AbstractA set of 24 identically made CdTe devices were subjected to accelerated lifetime testing (ALT) using open-circuit bias, 1 sun illumination, and heating under room ambient (dry) conditions at 60, 80, 100, and 120 *C. A total of 6 devices were tested at each temperature. Data was periodically collected for up to 2000+ hours. A systematic pattern of degradation became apparent with increased stress temperature. At 60-80 *C, degradation mechanisms associated with the CdTe/backcontact dominate. In this temperature regime, degradation modes include increased series resistance and increased backcontact barrier height resulting in increased 1st quadrant rollover. As temperature was increased above 80 *C, we observed a significant increase in voltage-dependent collection, which directly affected FF but not Voc. With higher ALT stress temperatures of 100-120 *C, recombination and loss in Voc were the dominant degradation modes. Increased voltage-dependent collection and recombination are believed to be associated with the forward-bias enhanced diffusion of Cu+ from the backcontact to the heterojunction during these ALT studies. This latter understanding was demonstrated by a parallel study using devices in which Cu introduced at the backcontact in a systematically controlled fashion. In these devices, Cu layers of thickness varying from 0 to 100 nm were evaporated onto CdTe devices that had undergone prior nitric-phosphoric etches. This etch produces a Te-rich layer on the surface of the CdTe within which evaporated Cu can react to form CuxTe. Time resolved photoluminescence measurements show a systematic decrease in bulk lifetime near the CdS/CdTe junction with increased evaporated Cu layer thickness. This decrease has been correlated with a decrease in device Voc. Quantum efficiency measurements have also confirmed a decrease in red response with increasing Cu that helps explain the voltage-dependent collection observed in devices stressed at higher ALT temperatures.Further validation of our belief that Cu migration is responsible for degradation modes observed at higher ALT stress temperatures was demonstrated by extracting activation energies from measured degradation rates as a function of time and temperature. Best-fit degradation (D) models using a power law type relationship were used to determine the effective life (L) of devices assuming a 10% drop in efficiency as the "definition" of useable life. Arrhenius-derived activation energies clearly associate an activation energy of 2.8 eV with the lower temperature degradation. The higher temperature activation energy was determined to be 0.63 eV, which agrees well with the literature value of 0.67 eV for Cu diffusion in CdTe. Thus, Cu diffusion is identified as the rate-dominating mechanism for degradation in our CdTe devices stressed at higher ALT temperatures.This abstract is subject to government rights.
12:30 PM - Y1.8
Investigation of ZnO:Al Doping Level and Deposition Temperature Effects on CIGS Solar Cell Performance.
Joel Duenow 1 2 , Timothy Gessert 2 , David Wood 1 , Brian Egaas 1 2 , Rommel Noufi 2 , Timothy Coutts 2
1 Dept. of Physics, Colorado School of Mines, Golden, Colorado, United States, 2 , National Renewable Energy Laboratory, Golden, Colorado, United States
Show Abstract12:45 PM - Y1.9
InGaAs Solar Cells Grown on Wafer-Bonded InP/Si Epitaxial Templates.
James Zahler 2 , Katsuaki Tanabe 1 , Corinne Ladous 2 , Thomas Pinnington 2 , Frederick Newman 3 , Harry Atwater 1 2
2 , Aonex Technologies, Pasadena, California, United States, 1 Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California, United States, 3 , Emcore Photovoltaics, Albuquerque, New Mexico, United States
Show AbstractSolar cells fabricated on InP/Si epitaxial templates formed by wafer bonding and layer transfer have potential for significant cost and weight reduction relative to cells fabricated on bulk InP substrates. InP/Si substrates could be used as epitaxial templates for InGaAsP/InGaAs dual-junction solar cells lattice-matched to InP as well as conventional InP single-junction cells. Ultimately, InP/Si epitaxial templates are extendable to fabrication of ultrahigh efficiency four-junction (4J) AlInGaP/GaAs/InGaAsP/InGaAs cells via a direct bond interconnect between subcell structures of InGaAsP/InGaAs grown on InP/Si and AlInGaP/GaAs grown on GaAs to form the overall 4J cell structure. In this work we report on the first known demonstration of InGaAs solar cell fabrication on wafer-bonded InP/Si epitaxial templates.InP films ~900 nm thick were transferred onto thermally-oxidized Si substrates via wafer bonding. Transfer of the InP thin film was induced by helium-implantation of the InP and annealing of the bonded InP/Si structure to exfoliate the film. The damaged surface region of the as-transferred InP film was removed using an etching process to leave a film of ~400 nm with a roughness of ~10 nm-rms, as measured by contact mode atomic force microscopy. InGaAs solar cells were grown on the InP/Si epitaxial templates by metalorganic chemical vapor deposition. The solar cells had an n-type InGaAs emitter and a p-type InGaAs base with bandgap energies of 0.74 eV and nominally lattice-matched to (001)InP. Photovoltaic current-voltage (I-V) characteristics of the 1 mm2 InGaAs cells were measured under AM1.5 Global solar spectrum with 1-sun total intensity (100 mW cm-2). For comparison, photovoltaic I-V characteristics of InGaAs cells grown on bulk epi-ready (001)InP substrates were also measured. The device parameters for the InGaAs cell grown on the wafer-bonded InP/Si epitaxial template were Jsc = 35.8 mA cm-2, Voc = 0.29 V, FF = 0.56, and η = 5.8%, where Jsc, Voc, FF and η are short-circuit current, open-circuit voltage, fill factor and energy conversion efficiency, respectively. This performance was comparable to that of the InGaAs cells grown on bulk (001)InP substrates, Jsc = 26.9 mA cm-2, Voc = 0.31 V, FF = 0.63, and η = 5.2%.
Y2: Novel Materials and Processes
Session Chairs
Ken Durose
Hans-Werner Schock
Tuesday PM, April 10, 2007
Room 2024 (Moscone West)
2:30 PM - **Y2.1
Issues for Composition Control in the Deposition of CuInSe2-based Alloys.
William Shafarman 1 , Robert Birkmire 1 , Shiro Nishiwaki 1 , Greg Hanket 1
1 Institute of Energy Conversion, University of Delaware, Newark, Delaware, United States
Show AbstractThe composition of Cu(InGa)Se2 thin films grown by elemental evaporation is controlled in a predictable manner by the delivery of the elemental fluxes. Under typical deposition conditions, the Cu and Se are distributed uniformly through the bulk of the film while the Ga and In distributions are determined by their flux–time profiles during growth. However, with different alloys and growth processes the film composition can be controlled by other factors which will be described in this work. The formation of stable intermetallic phases plays a critical role in the growth of CuAlSe2 by elemental evaporation and in the composition control of Cu(InGa)Se2 or Cu(InGa)(SeS)2 by the reaction of metal precursors. In each case, procedures to overcome the formation of the intermetallic phases and form single phase chalcopyrite materials with controlled composition will be described. In the elemental evaporation of CuIn(SeS)2 or Cu(InGa)(SeS)2 the relative incorporation of the chalcogen species is controlled by the presence of excess Cu and the effects of film composition versus relative flux variation will be described.
3:00 PM - Y2.2
Fabrication and Characterization of Cd1-xMgxTe Thin Films and Their Application in Solar Cells
Ramesh Dhere 1 , Kannan Ramanathan 2 , John Scharf 1 , Bobby To 1 , Anna Duda 1 , Helio Moutinho 1 , Rommel Noufi 1
1 , National Renewable Energy Lab, Golden, Colorado, United States, 2 , MiaSole, Santa Clara, California, United States
Show AbstractTwo-junction tandem solar cells require a top cell with a bandgap in the range of 1.6–1.8 eV. Ternary alloys of CdTe are of great interest for this application because of the success of CdTe solar cells. Considerable work has been conducted on Cd1-xZnxTe (CZT) polycrystalline thin films, but the development of CZT solar cells is hampered by the high affinity of Zn to oxygen and chlorine, which are routinely used in fabricating high-efficiency CdTe solar cells. Cd1-xMgxTe (CMT) offers several unique advantages, such as a large change in bandgap for the same composition as compared to CZT. The lattice mismatch between CdTe and CMT is minimal in the entire composition range, and the alloy retains the sphalerite structure of CdTe in a wide composition range. In this paper, we present our work on developing CMT polycrystalline thin films. CMT thin films were fabricated by co-evaporation of CdTe and Mg at a substrate temperature of 400ο C. The spatial separation of the two sources resulted in a compositional gradient, which allowed the deposition of a wide range of compositions from fewer runs. Stable films for compositions up to x=0.73 were fabricated, and the structural properties of the samples were studied by X-ray diffraction. The data show that the films have a sphalerite structure and are preferentially oriented in the <111> direction, and the lattice constant varies linearly with composition. Optical analysis of the samples shows that the optical bandgap varies linearly with composition and can be described byEg(x) = 1.6 x + 1.46 eV.The optical absorption coefficient of the alloy films for the entire composition range (up to x=0.73) is over 6x104/cm for energies above the bandgap, indicating a direct-gap semiconductor. We have fabricated solar cells using these films with the following structure: glass / SnO2 / CdS / CMT / back contact. Using the same processing conditions used for CdTe solar cells, the device efficiency was less than 2%. Post-deposition chloride heat-treatment in oxygen ambient resulted in partial dissociation of the CMT alloy and loss of Mg. With modified contact processing, we were able to improve efficiencies to over 5%. With modified chloride processing, we were able to minimize alloy decomposition and further improve the efficiencies. We have obtained devices with open-circuit voltages of up to 845 mV and efficiencies of 8% for CMT devices with a bandgap in the range of 1.6–1.62 eV. We will present a detailed analysis of the device properties and their correlation to materials properties of CMT. This abstract is subject to government rights.
3:15 PM - Y2.3
Nanostructured ZnS:In2S3 Buffer Layers. Can Voltage and Efficiency be Improved Through Interface Inhomogeneities on a Scale Below the Minority Carrier Diffusion Length?
Nicholas Allsop 1 , Andreas Haensel 1 , Christian Camus 1 , Sophie Gledhill 1 , Iver Lauermann 1 , Christian Fischer 1 , Martha Lux-Steiner 1
1 Solar Energy - Heterogeneous Material Systems, Hahn-Meitner-Institute, Berlin Germany
Show Abstract3:30 PM - Y2.4
Experimental and Theoretical Study of Fluorine Doping to Tin Oxide.
Xiaonan Li 1 , Sally Asher 1 , Joel Pankow 1 , Lei Kerr 2 , Mailasu Bai 3 , Timothy Gessert 1
1 5200, National Renewable Energy Laboratory, Golden, Colorado, United States, 2 , Miami University of Ohio, Oxford, Ohio, United States, 3 , Colorado School of Mines, Golden, Colorado, United States
Show AbstractConductive tin-oxide (SnO2) films on glass substrates are used extensively for transparent electrodes in thin-film photovoltaic solar cells, electrochromic devices, flat-panel displays, and gas sensors. SnO2 with a tetragonal structure is naturally an n-type semiconductor because of a deviation from stoichiometry. The best n-type dopants for SnO2 is fluorine. With it, the electron concentration of 5-10^20/cm^3, and μ of 40 cm^2/V-s has achieved. However, the commonly used fluorine dopant for research used SnO2 film, bromotrifluoromethane (CBrF3), is a green–house gas. Thus, the alternative fluorine source is needed to replace the CBrF3. In this study, we first estimated the doping efficiency for different dopant precursors (CF4, CBrF3, and CIF3). We find that CIF3 is a most reactive precursor in the three precursors that studied. The reactivity of CF4 is much lower than the other two precursors. This prediction is consistent with the experimental observation. Then we did experiments to studied CIF3 source as replacement. The electric and optical properties of the SnO2 film that doped by CBrF3 and CIF3 source are compared. The effects of deposition temperature, different dopant and oxygen gas flow rates are studied. We found that due to the high volatility of CBrF3 precursor, the fluorine doping efficiency is strongly dependent on the substrate temperature and reaction chamber pressure. As a comparison, to achieve the similar carrier concentration, far less CIF3 dopant is required. However, for similar film thickness, with the CIF3 doping, the SnO2 film has lower mobility (<30 cm^2/Vs) and higher optical absorption compared with the films doped with CBrF3.This abstract is subject to government rights.
3:45 PM - Y2.5
Development of a Wide Band Gap Cd1-xMgxTe Film for Applications in Tandem Devices.
Xavier Mathew 1 2 , Anthony Vasko 1 , Jennifer Drayton 1 , Alvin Compaan 1
1 Physics and Astronomy, Univ. of Toledo, Toledo, Ohio, United States, 2 CIE, UNAM, Temixco, Morelos, Mexico
Show Abstract4:30 PM - **Y2.6
Zn-based Buffer Layer and High-quality CIGS Films Grown by a Novel Method.
Akira Yamada 1 , Fanying Meng 1 , Yoshiyuki Chiba 2 , Makoto Konagai 2
1 Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, Tokyo Japan, 2 Department of Physical Electronics, Tokyo Institute of Technology, Tokyo Japan
Show Abstract5:00 PM - Y2.7
Growth and Characterization of Chalcopyrite Nanocrystals: Beyond Conventional Thin Films.
David Fuertes Marron 1 , Sebastian Lehmann 1 , Sascha Sadewasser 1 , Martha Ch. Lux-Steiner 1
1 Department of Solar Energy, Hahn-Meitner Institut, Berlin Germany
Show Abstract5:15 PM - Y2.8
Transparent Back Contacts in CdTe/CdS: Evaluation for Tandem Cells.
Viral Parikh 1 , Anthony Vasko 1 , Alvin Compaan 1
1 Physics and Astronomy, University of Toledo, Toledo, Ohio, United States
Show AbstractBy using a transparent back contact (TBC), a CdTe/CdS cell may be transparent to photons with energy less than the 1.5 eV bandgap of CdTe. This allows CdTe cells to be used as a top cell in a tandem structure, of either the two- or four-terminal kind. We have fabricated CdTe cells with transparent back contacts yielding efficiencies of up to 9%. We have evaluated the back contacts in terms of cell efficiency and transparency using combinations of p-type ZnTe:N and ZnTe:Cu, with n-type ZnO:Al and ITO (for total combinations of ZnTe:N/ZnO:Al, ZnTe:N/ITO, ZnTe:Cu/ZnO:Al, and ZnTe:Cu/ITO). CdTe thicknesses from 0.6 to 2.5 micrometers have been used. CdTe of lesser thickness may transmit some above bandgap photons, allowing for current matching in two terminal devices. We have performed bifacial IV and QE characterization under varying degrees of white light bias. Modeling has been employed to extract information on depletion widths and drift and diffusion lengths, and to understand the impact of TBC materials on the carrier collection from the primary junction. Acknowledgements – This work is supported by the NREL high performance PV program.
5:30 PM - Y2.9
An Indium Free Transparent Conductive Oxide: doped TiO2.
M. van Hest 1 , M. Gillispie 2 , M. Dabney 1 , J. Perkins 1 , D. Ginley 1
1 , National Renewable Energy Laboratory, Golden, Colorado, United States, 2 , Iowa State University, Ames, Iowa, United States
Show AbstractMost of the commonly used transparent conductive oxides (TCO) contain indium. Due to its cost, there is a clear need for an indium free alternative. Doped anatase TiO2 thin films grown on SrTiO3 (STO) using pulsed laser deposition (PLD) have been shown to be viable In-free transparent conductors with conductivities of 3500-5000 S/cm for 40 nm thick films. Little is known about this material. Here, we will show a detailed study of this material deposited by PLD and sputtering. This study demonstrates that the conductivity in this material is a bulk effect. It is also demonstrated that the TiO2 needs to be biaxially textured (004) anatase in order to be highly conductive. Since PLD is most likely not a viable way of deposition for large area, alternative methods for deposition of this material are studied. It is demonstrated that doped anatase TiO2 films can be deposited by RF magnetron sputtering. Thin films of Ti0.85Nb0.15O2 were deposited on STO and glass substrates using a ceramic oxide target at varying substrate temperatures in a pure Ar atmosphere. For films grown on STO, conductivity as high as 1500 S/cm has been obtained. X-ray diffraction (XRD) analysis showed that the most conductive films were (004)-textured anatase TiO2. Films grown on glass showed a maximum conductivity of ~100 S/cm, 15x smaller than films on STO. This decrease in conductivity is largely due to a decreased mobility. XRD analysis for the most conductive films on glass showed randomly oriented anatase TiO2.
5:45 PM - Y2.10
Towards Lower Deposition Temperatures of Spray Deposited ZnO Films.
Sophie Gledhill 1 , Pablo Thier 1 , Nicholas Allsop 1 , Martha Lux-Steiner 1 , Christian Herbert Fischer 1
1 Solar Energy 2, Hahn-Meitner Institute, Berlin Germany
Show AbstractY3: Posters
Session Chairs
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - Y3.1
In-situ Characterization of As-grown Surface of CIGS Films.
Hirotake Kashiwabara 1 , Shimpei Teshima 1 , Kazuya Kikunaga 1 , Kazunori Takeshita 1 , Tetsuji Okuda 1 , Kozo Obara 1 , Keiichiro Sakurai 2 , Shogo Ishizuka 2 , Akimasa Yamada 2 , Koji Matsubara 2 , Shigeru Niki 2 , Norio Terada 1 2
1 Nano-Structure and Advanced Materials, Kaghosima University, Kagoshima Japan, 2 Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, Tsukuba Japan
Show AbstractControl of hetero interfaces in Cu(In1-xGax)Se2 [CIGS] based solar cells is one of the keys for pursuing higher conversion efficiency. For the interface between CdS buffer grown by chemical bath deposition (CBD) and In-rich CIGS absorber, it has been repeatedly observed that the CIGS region adjacent to the interface has Cu-deficient composition and much wider band gap energy about 1.3 eV, with respect to those of the corresponding bulk. It has been recognized that the presence of this wide gap region would suppress the carrier recombination and cause a notable improvement of cell-performances. Understanding of formation mechanism of the wide gap surface-region of CIGS is, therefore, important for the precise control of the interface. There are, however, few experimental reports about it. Theoretical calculations have indicated the structural instability of stoichiometric surface of CIGS, and stabilization of it by introduction of Cu-vacancies. It suggests the self-formation of Cu-deficient surface during growth process of CIGS. On the other hand, serious modifications of the CIGS surfaces in CBD process is also pointed out, since Cu ions in CIGS could be selectively dissolved in the bath.In order to determine in which sequence the wide gap region is formed, chemical formula and electronic structure of the as-grown CIGS layer by in-situ XPS, UPS and IPES.Specimen films with a nominal composition of Cu0.93(In0.65Ga0.35)Se2 were grown by conventional three stage co-evaporation. They were transported to the analysis system by using a vacuum vessel. During the transportation, pressure of the vessel was maintained at mid 10-9 Torr or better. This method yielded a clean feature of the as-received surfaces; carbon and oxygen were below detection limit of XPS.The as-grown surface exhibited seriously Cu and Ga depleted composition: Cu/(Cu+In+Ga+Se) = 0.08 ~ 0.10, Cu/(In+Ga) = 0.29 ~ 0.31 and Ga/(In+Ga) = 0.15. Though slow increases of these ratios were observed in the depth profile, the region 10 ~ 20 nm under the original surface had Cu/(Cu+In+Ga+Se) = 0.14, Cu/(In+Ga) = 0.40 and Ga/(In+Ga) = 0.38, which are between so-called 1-3-5 and 1-5-8 Cu-deficient phases. These results revealed that the Cu and Ga deficient phase is already formed in the final stage of the growth of CIGS.UPS/IPES measurements of the as-gr