Key issue for the fabrication of high-efficiency microcrystalline silicon thin-film solar cells at low temperatures

Hydrogenated microcrystalline silicon (muc-Si:H) p-i-n solar cells have been prepared using the plasma-enhanced chemical vapor deposition (PECVD) method at process temperatures lower than 150degreesC. The low-temperature deposition of pc-Si:H was found to be effective in suppressing the formation of oxygen-related donors that cause a reduction of the open circuit voltage (V-OC). We demonstrate the increase in V-OC by lowering the deposition temperature to less than 150degreesC without deteriorating other device parameters such as short circuit current (J(SC)) and fill factor (FF), A high efficiency of 8,91, was obtained on a textured SnO2 substrate (Asahi-U) substrate. Further improvement in the efficiency to 9.4% (V-OC = 0.526 V J(SC) = 25.3 mA/cm(2), F-F = 0.710) was achieved by optimizing the texture of Ga-doped ZnO substrates. An attempt to increase the deposition rate is also demonstrated using 60 MHz plasma and a relatively high efficiency of 8.4% as obtained at a deposition rate of 12 Angstrom/s.