Use of Very High Frequency Plasmas to Prepare a-SiGe Alloy Photovoltaic

The program objective is to investigate the feasibility of using a very high frequency (VHF) [70 MHz] plasma technique to produce high efficiency a-SiGe:H solar cells at relatively high deposition rates. Using the VHF technique, high quality a-SiGe:H material is expected due to enhanced low energy ion bombardment of the growing film surface which has been found to be beneficial to the growth of this type of alloy. A group from Neuchatel University have demonstrated that by using the VHF technique, a-Si:H material can be prepared at the high rate of 10 /sec without a deterioration in the electronic properties. Thus, with the expected faster deposition rates and improved a-SiGe:H solar cell efficiencies, application of this technique to ECD's existing roll-to-roll solar cell production process should lead to significant cost savings. For the Phase 1 program, we will produce and characterize a-SiGe:H materials using VHF process. In addition, utilizing ECD's expertise in a-Si technology, we will further advance this technology and fabricate single junction solar cells to demonstrate the advantages of using this technology. In later stages of the program, we will use the VHF technique to develop high efficiency triple junction devices and scale up the process for the commercial production.