High-throughput combinatorial approaches have been used for the discovery and optimization of transparent conducting oxide (TCO) materials for PV applications. We report on current investigations in In-Zn-O, In-Ti-O and In-Mo-O systems. The InZnO system is shown to be amorphous in the best conducting range with a conductivity of ~ 3000 &#937;-cm-1 for 50%-70% In/Zn. The amorphous InZnO films are very smooth (2..ANG.. rms). In-Ti-O is found to be an excellent high-mobility TCO with mobilities of greater than 80 cm2/v-sec and conductivities of more than 6000 &#937;-cm-1 for sputtered thin film materials

Alleman, J. L.

Dabney, M. S.

Gedvilas, L. M.

Ginley, D. S.

Keyes, B. M.

Perkins, J. D.

Readey, D.

Taylor, M. P.

Teplin, C. W.

To, B.

van Hest, M. F. A. M.

Young, D.

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 A national laboratory of the U.S. Department of EnergyOffice of Energy Efficiency & Renewable EnergyNational Renewable Energy Laboratory Innovation for Our Energy Future Combinatorial Exploration of Novel Transparent Conducting Oxide Materials D.S. Ginley, M.F.A.M. van Hest, D. Young,  C.W. Teplin, J.L. Alleman, M.S. Dabney, P. Parilla, L.M. Gedvilas, B.M. Keyes, B. To, and J.D. Perkins National Renewable Energy Laboratory M.P. Taylor and D. Readey Colorado School of Mines Presented at the 2005 DOE Solar Energy Technologies  Program Review Meeting November 7–10, 2005 Denver, Colorado Conference Paper NREL/CP-520-38999 November 2005 NREL is operated by Midwest Research Institute ● Battelle     Contract No. DE-AC36-99-GO10337  NOTICE The submitted manuscript has been offered by an employee of the Midwest Research Institute (MRI), a contractor of the US Government under Contract No. DE-AC36-99GO10337. Accordingly, the US Government and MRI retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.  Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof.  The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at http://www.osti.gov/bridgeAvailable for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone:  865.576.8401 fax: 865.576.5728 email:  mailto:reports@adonis.osti.govAvailable for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone:  800.553.6847 fax:  703.605.6900 email: orders@ntis.fedworld.gov online ordering:  http://www.ntis.gov/ordering.htmPrinted on paper containing at least 50% wastepaper, including 20% postconsumer waste Combinatorial Exploration of Novel Transparent Conducting Oxide Materials David S. Ginley1, Matthew P. Taylor2, Maikel F.A.M. van Hest1, David Young1, Charles W. Teplin1, Jeff L. Alleman1, Matthew S. Dabney1, Phil Parilla1, Lynn M. Gedvilas1, Brian M. Keyes1, Bobby To1, Dennis Readey2,  and John D. Perkins1 1National Renewable Energy Laboratory, Golden, Colorado, david_ginley@nrel.gov 2Colorado School of Mines, Golden, CO 80401  ABSTRACT High-throughput combinatorial approaches have been used for the discovery and optimization of transparent conducting oxide (TCO) materials for PV applications. We report on current investigations in In-Zn-O, In-Ti-O and In-Mo-O systems. The InZnO system is shown to be amorphous in the best conducting range with a conductivity of ~ 3000 Ω-cm-1 for 50%-70% In/Zn.  The amorphous InZnO films are very smooth (2 Å rms).  In-Ti-O is found to be an excellent high-mobility TCO with mobilities of greater than 80 cm2/v-sec and conductivities of more than 6000 Ω-cm-1 for sputtered thin film materials. 1. Technical Approach The discovery and optimization of new materials and devices for photovoltaic applications is nominally a slow and time-consuming process.  The advent of high-speed automated analysis and data-handling tools has enabled the use of combinatorial high­throughput approaches to photovoltaic materials. High-throughput combinatorial approaches have shown applicability in a wide range of materials areas including catalysis, inorganic synthesis, new materials discovery, device development, and organic synthesis. The advent of computer-automated deposition, analysis, and data-mining capabilities has enabled the broad application of these approaches.  NREL has specifically worked for the past five years on the development of the appropriate tools for the discovery and optimization of optoelectronic materials and devices including TCOs and amorphous Si.   2. Results and Accomplishments In the TCO area, we have developed a set of deposition tools (two systems) capable of depositing up to quartenary materials systems by sputter deposition with and without ion beam assist2. The ion­beam-assist mode is often helpful to optimize properties at lower deposition temperatures. A set of complementary analytical capabilities has been developed to examine the compositionally graded libraries.  These are specifically tailored for TCO materials and all handle at least 2”x2” libraries.  They include: a mapping x-ray diffraction system; a mapping simultaneous reflection transmission system (200nm­2000 nm); mapping FTIR; a four-probe system for mapping conductivity; mapping atomic-force, scanning-electron and EDS microscopy; a mapping micro-Raman system; mapping for corrosion analysis; and work function measurement by Kelvin probe.  This core set of tools, coupled to appropriate data-basing and modeling, can rapidly evaluate very large phase spaces in weeks or months that would have taken years by conventional approaches. These tools have been applied to a number of relevant TCO systems including ZnSnO 3, InZnO 2,4, Mo:In2O3 and Ti: In2O3 5. In this paper, we discuss results on indium-oxide-based systems doped with Mo and Ti and substituted with Zn.  The InZnO system is shown to be amorphous in the best conducting range (50%­70% In) as shown in Fig. 1 and films are deposited at room temperature and are very smooth (2 Å rms). In the amorphous range, films have a conductivity of 3000 Ω-cm-1 2. More interesting, as can be seen in Fig. 2, the amorphous phase is remarkably stable under thermal annealing (in this case Ar), showing no crystallization and very little conductivity change to 600°C over 10 hours of annealing.  This indicates that amorphous TCOs may be well suited to OLED applications. Fig. 1. Conductivity, RMS roughness, and refractive index and crystalline phase fields for as-deposited In-Zn-O. The Mo- and Ti-doped materials we have explored by combinatorial approaches have demonstrated outstanding properties with mobilities of greater than 80 cm2/v-sec and conductivities of  greater  than 6000  1   Fig. 2. Effect of annealing in air (top) and argon (bottom) on the conductivity and structure of In-Zn-O Ω-cm-1 as shown in Fig. 3 for the Ti-doped In2O3 system 5. However, their optimum process temperature is more than 400°C and thus they may not be optimal for organic applications. Note, however, that the work function (ie contact potential difference) varies by almost half a volt. It was only through the application of the high-throughput techniques that this range of compositions could be explored. Once interesting phase regions are identified, then single composition samples are evaluated by pulse laser deposition or sputtering using in-house target fabrication and deposition system capabilities 1. Fig. 3. Electrical properties and work function of Ti-doped In2O3. ACKNOWLEDGEMENTS The NREL work was performed under DOE contract DE-AC36-99-GO10337. REFERENCES 1C. Warmsingh, Y. Yoshida, D. W. Readey, C. W. Teplin, J. D. Perkins, P. A. Parilla, L. M. Gedvilas, B. M. Keyes, and D. S. Ginley, Journal of Applied Physics 95, 3831-3833 (2004).  2M. P. Taylor, D. W. Readey, C. W. Teplin, M. F. A. M. van Hest, J. L. Alleman, M. S. Dabney, L. M. Gedvilas,  B. M. Keyes, B. To, J. D. Perkins, and D. S. Ginley,  Measurement Science and Technology 16, 90 (2005). 3J. D. Perkins, J. A. del Cueto, J. L. Alleman, C.  Warmsingh, B. M. Keyes, L. M. Gedvilas, P. A. Parilla,  B. To, D. W. Readey, and D. S. Ginley, Thin Solid  Films 411, 152 (2002).  4M. P. Taylor, D. W. Readey, C. W. Teplin, M. van  Hest, J. L. Alleman, M. S. Dabney, L. M. Gedvilas, B.  M. Keyes, B. To, P. A. Parilla, J. D. Perkins, and D. S.  Ginley, Macromolecular Rapid Communications 25, 344-347 (2004).  5M. van Hest, M. S. Dabney, J. D. Perkins, D. S.  Ginley, and M. P. Taylor, Applied Physics Letters 87, 032111 (2005).  MAJOR FY 2005 PUBLICATIONS See references 2, 4 and 5 above. 2 REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) November 2005 2. REPORT TYPE Conference Paper 3. DATES COVERED (From - To)       5a. CONTRACT NUMBER DE-AC36-99-GO10337 5b. GRANT NUMBER  4. TITLE AND SUBTITLE Combinatorial Exploration of Novel Transparent Conducting Oxide Materials 5c. PROGRAM ELEMENT NUMBER  5d. PROJECT NUMBER NREL/CP-520-38999 5e. TASK NUMBER PVA6.4201 6. AUTHOR(S) D.S. Ginley, M.P. Taylor, M.F.A.M. van Hest, D. Young,  C.W. Teplin, J.L. Alleman, M.S. Dabney, P. Parilla, L.M. Gedvilas, B.M. Keyes, B. To, D. Readey, and J.D. Perkins 5f. WORK UNIT NUMBER  7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) National Renewable Energy Laboratory 1617 Cole Blvd. Golden, CO 80401-3393 8. PERFORMING ORGANIZATION REPORT NUMBER NREL/CP-520-38999 10. SPONSOR/MONITOR'S ACRONYM(S) NREL 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)  11. SPONSORING/MONITORING AGENCY REPORT NUMBER  12. DISTRIBUTION AVAILABILITY STATEMENT National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 13. SUPPLEMENTARY NOTES  14. ABSTRACT (Maximum 200 Words) High-throughput combinatorial approaches have been used for the discovery and optimization of transparent conducting oxide (TCO) materials for PV applications.  We report on current investigations in In-Zn-O, In-Ti-O and In-Mo-O systems. The InZnO system is shown to be amorphous in the best conducting range with a conductivity of ~ 3000 Ω-cm-1 for 50%-70% In/Zn.  The amorphous InZnO films are very smooth (2 Å rms).  In-Ti-O is found to be an excellent high-mobility TCO with mobilities of greater than 80 cm2/v-sec and conductivities of more than 6000 Ω-cm-1 for sputtered thin film materials. 15. SUBJECT TERMS Photovoltaics; solar; transparent conducting oxide; PV; NREL 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON  a. REPORT Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified 17. LIMITATION OF ABSTRACTUL 18. NUMBER OF PAGES  19b. TELEPONE NUMBER (Include area code)  Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 

Combinatorial Exploration of Novel Transparent Conducting Oxide Materials

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Combinatorial Exploration of Novel Transparent Conducting Oxide Materials

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