Advanced Processing Technology for High-Efficiency, Thin-Film CuInSe2 and CdTe Solar Cells: Final Subcontract Report, 1 March 1992 - 30 April 1995

This report describes work performed by the University of South Florida to develop a manufacturing-friendly fabrication process for CulnSe2 (CIS) solar cells. The process developed under this project uses conventional deposition processes and equipment, does not require stringent process control, and uses elemental Se as the selenium source. We believe it can be readily scaled up using off-theshelf processing equipment and that it will meet the low manufacturing-cost objectives. Another significant achievement under this project was the development of a reactive sputtering deposition technology for ZnO. ZnO is used in many solar cell devices, and sputtering is a desirable manufacturing technology. The application of sputtering has been limited because conventional deposition usesceramic targets that result in low sputtering rates. The use of Zn metal as the target in reactive sputtering overcomes this limitation: We have demonstrated that ZnO deposited by reactive sputtering has state-of-the-art opto-electronic properties. These developments result in large-area uniformity and optimized performance and provide a significant opportunity for applying and commercializingthe technology. The second objective of this project was to fabricated high-efficiency CdTe solar cells using manufacturing-friendly processes. Three deposition processes were used to deposit CdS films: chemical bath deposition, rf sputtering, and close-spaced sublimation (CSS). The CdTe films were deposited by CSS. A cell with a record efficiency of 1 5.8% was obtained.