Low temperature μc-Si film growth using a CaF2 seed layer

This paper describes low temperature thin film Si growth by remote plasma chemical vapor deposition system for photovoltaic device applications. Using CaF2/glass substrate, we were able to achieve an improved μc-Si film at a low process temperature of 300°C. The μc-Si film on CaF2/glass substrate shows that a crystalline volume fraction of 65% and dark conductivity of 1.65×10−8 S/cm with the growth conditions of 50 W, 300°C, 88 mTorr, and SiH4/H2=1.2%. XRD analysis on μc-Si/CaF2/glass showed crystalline film growth in (1 1 1) and (2 2 0) planes. Grain size was enlarged as large as 700 Å for a μc-Si/CaF2/glass structure. Activation energy of μc-Si film was given as 0.49 eV. The μc-Si films exhibited dark- and photo-conductivity ratio of 124.