Microcrystalline silicon for solar cells, deposited at high rate by VHF-GD at high pressure

Microcrystalline silicon (/spl mu/c-Si:H) is an attractive indirect low-band gap absorber material for thin-film solar cells. However, due to the thick absorber layers needed, high deposition rates are required to achieve cost reduction for industrial production. Therefore a comparison of state-of-the-art, high-rate techniques is needed. In this study, the impact of high deposition pressures on the growth of /spl mu/c-Si:H has been investigated, applied to the VHF-GD PECVD deposition process. Hereby, /spl mu/c-Si:H layers deposited at rates up to 25 /spl Aring//s were obtained. These films show device-grade quality, e.g. the defect absorption (as measured by CPM) is low enough (/spl alpha/(0.8 eV)/spl ap/2 cm/sup -1/) and "midgap" character: from dark current measurements (/spl sigma//sub d/) is obtained. The present contribution deals with a loss of quantum efficiency for longer wavelengths encountered while incorporating such high-rate layers into full pin-type /spl mu/c-Si:H solar cells.