Post-crystallisation treatment and characterisation of polycrystalline silicon thin-film solar cells on glass

Abstract

Polycrystalline silicon on glass is a possible thin-film material for photovoltaic applications. This thesis performs a detailed experimental investigation of the impacts of two post-crystallisation process steps (rapid thermal annealing and hydrogenation) on the electrical properties of poly-Si on glass diodes. The optimum RTA peak temperature is determined to be about 1000 &176;C, whereby this process shifts the p-n junction by 0.55 microns into the absorber layer. By optimising the hydrogenation process in a reactor with four linear microwave plasma sources, the lateral non-uniformity of the open-circuit voltage is reduced to less than &177; 3% over an area of 400 cm&178;. We find that the ratio of ECV to Hall average doping concentration for most of our poly-Si films lies in the range of 1.6 to 2.2. Cross-sectional electron beam-induced current measurements reveal that the p-n junction of our textured samples is disrupted and non-conformal due to the texture features.