Preparation Temperature Effects in Microcrystalline Silicon Thin Film Solar Cells

Abstract

ABSTRACTMicrocrystalline silicon solar cells were prepared at various substrate temperatures using a plasma enhanced chemical vapor deposition technique at 95 MHz. Devices in superstrate configuration, i.e. prepared on transparent glass/ZnO substrates with deposition sequence p-i-n, suffer from a reduction of short wavelength response upon increasing substrate temperature. As underlying mechanism adverse effects on the p-i interface region are discussed. For devices in substrate configuration (deposition sequence n-i-p on Ag/ZnO back-reflectors) a pronounced efficiency maximum with a highest value of 8.7 % is observed at substrate temperatures of about 250 °C. Comparing the dark J-V characteristics obtained for different device thicknesses at substrate temperatures of 200 °and 250 °C, respectively, improved i-layer material and transport properties are suggested in the latter case. The results illustrate the sensitivity ofmicrocrystalline silicon devices with respect to the employed substrate temperature by effects on the absorber layer material properties on the one hand and by effects related to the device design, e.g. the specific deposition sequence of the individual layers, on the other hand.