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Siemens Solar Industries (SSI) achieved outstanding progress toward NREL/DOE goals during this subcontract. The statistical process control methodology was applied, and it demonstrated process reproducibility and yields for a 10-cm {times} 10-cm substrate size baseline process. Based on an understanding of the importance of materials of construction and the physical layout for absorber formation reactors, SSI designed and built a replacement large-area reactor based on a more direct scale-up of the baseline reactor. While designing and building the new large-area reactor, SSI defined and demonstrated new package designs to combine 10-cm {times} 30-cm circuit plates into one package; this allowed SSI to deliver large-area prototype modules to NREL for evaluation, and to introduce the first CIS-based products--5-watt (ST5) and 10-watt (ST10) modules. After completion of the new large-area reactor, all processes were scaled to a 30-cm {times} 120-cm plate size. Subsequently, only large 30-cm {times} 120-cm circuit plates were fabricated for 30-cm {times} 120-cm prototype modules or, after cutting the large circuit plates into smaller circuit plates, for the two new CIS-based products. The scaled process exhibits generally good control for extended periods with periodic shifts in the short-term process average that appears to result from batch-to-batch variability in precursormore » or base electrode preparation. Similarly, periodic shunting along the laser-scribed pattern lines in the Mo base electrode appears to result from batch-to-batch variability in base electrode preparation. Significant progress was made in understanding transient effects in CIS devices. Transient effects are important for many topics, including accelerated testing, process definition, measurement protocols, process predictability, interpretation of experimental test results, and understanding of device structures. Long-term outdoor stability of CIS continues to be demonstrated at NREL where 30-cm {times} 30-cm and 30-cm {times} 120-cm modules have undergone testing for more than ten years. SSI delivered two sets of upgraded modules for 1-kW arrays to the NREL Outdoor Test Facility. Improvements in efficiency and the temperature coefficient for power were demonstrated for these modules with sulfur incorporated to form a graded (Cu(In,Ga)(Se,S){sub 2}) absorber. The NREL-measured average module efficiency at standard test conditions is 11.4% for the second array, and the efficiency of all modules far exceeds the DOE year 2000 goal of 10% for commercial CIS modules. SSI demonstrated a succession of NREL-confirmed world-record efficiencies culminating in demonstration of an 11.8 %-efficient, large-area, 3,651-cm{sup 2} module.« less |
