Technology Support for High-Throughput Processing of Thin-Film CdTe PV Modules: Phase II Annual Technical Report, 1 April 1999--31 March 2000

Results and conclusions from Phase II of a three-year subcontract are presented. The subcontract, entitled 'Technology Support for High-Throughput Processing of Thin-Film CdTe PV Modules,' is First Solar's portion of the Thin-Film Photovoltaic Partnership Program. The research effort of this subcontract is divided into four areas of effort: 1) process and equipment development, 2) efficiencyimprovement, 3) characterization and analysis, and 4) environmental, health, and safety. As part of the process and equipment development effort, a new semiconductor deposition system with a throughput of 3 m2/min was completed, and a production line in a new 75,000 ft2 facility was started and is near completion. As part of the efficiency-improvement task, research was done on cells and moduleswith thin CdS and buffer layers as way to increase photocurrent with no loss in the other photovoltaic characteristics. A number of activities were part of the characterization and analysis task, including developing a new admittance spectroscopy system, with a range of 0.001 Hz to 100 kHz, to characterize cells. As part of the environmental, health, and safety task, the methanol-based CdCl2process was replaced with aqueous-CdCl2. This change enabled the retention of a 'De Minimus' level of emissions for the manufacturing plant, so no permitting is required.