A-Si:H Solar Cells Deposited Using VHF–PECVD

a-Si:H p{sup +}-i-n{sup +} solar cells have been made employing plasma enhanced chemical vapor deposition at frequencies between 30--80 MHz. Here, only the i-layer was fabricated at these very high frequencies (VHF). Both the p{sup +}- and n{sup +}-layer were made using 13.56 MHz. A previous study has shown the material quality to depend on mainly the applied rf-power, and only slightly on the frequency. It should be noted that for homogeneity reasons a certain optimized pressure is required for each frequency. There is a clear correlation between material quality and solar cell parameters. An initial efficiency of 10% has been obtained for cells deposited at 65 MHz using a low power density, while the deposition rate still is 2--3 times higher than the one at 13.56 MHz. Light-soaking reveals stabilization at 6% for the best cell, which compares well to conventional 13.56 MHz cells.