Corp. are gratefully acknowledged. We would like to specially thank Professor Xunming Deng for the many discussions and input he has made in advancing this program he previously led. 2 Executive Summary ObjectivesThe main objective of this program is to develop a high rate thin film deposition method in order to increase the throughput of ECD's roll-to-roll solar module production design and in doing so reduce the cost of the solar modules. In particular, a very high frequency (70 MHz) plasma enhanced chemical vapor deposition (PECVD) process is being developed for the fabrication of intrinsic layers for high efficiency amorphous silicon-based triple-junction solar cells at high deposition rates. Intrinsic layers consisting of either amorphous silicon or amorphous silicon germanium alloy materials are being developed. The program goal is to prepare these materials at rates of 10 Å/s or higher while maintaining the cell efficiencies at the high values presently obtained for devices made using the standard 13.56 MHz frequency and low deposition rates (near 1 Å/s). Upon completion of a successful program, this high rate process will be added to ECD's roll-to-roll solar cell production design to reduce solar module cost. ApproachIn order to test the feasibility of using the VHF method for high rate intrinsic layer preparation, the deposition conditions used to prepare small area (0.25 cm 2 ) single-junction amorphous silicon (a-Si:H) and silicon germanium alloy (a-SiGe:H) cells by the very high frequency (VHF) technique are being optimized to obtain the highest cell efficiencies. These component cells will then be combined to create high efficiency a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cells. The deposition conditions for these multi-junction cells will also be optimized to further increase the device performance. In particular for the triple-junction cells, the conditions used to prepare p/n tunnel junctions will be optimized to minimize absorption and series resistance and maximize carrier collection and cell performance. Besides achieving high small area cell performance, large area cathode hardware designs which will allow for the uniform deposition of i-layers over a large area using the VHF technique and high deposition rates will be tested using a single chamber vacuum system. This large area hardware will be required for the future incorporation of the technique into an ECD built roll-to-roll solar cell production line. Results/StatusThe following has thus far been achieved during this year: 1) 8.0% stable efficiencies have been achieved for a-Si:H single-junction cells whose i-layers are prepared at rates near 10 Å/s using the VHF technique. This performance compares with 8.2% stabilized efficiencies for a-Si:H cells made using the same deposition equipment, the standard 13.56 MHz technique and deposition rates near 1 Å/s. While we have yet to achieve the 8.4% program goal for the a-Si:H cells, we hope that our recent improvement of the n-layer conditions as well as further optimization of other depositi...