Study of crystallinity in μc-Si:H films deposited by cat-CVD for thin film solar cell applications

The crystallinity of the hydrogenated microcrystalline silicon (μc-Si:H) film was known to influence the solar cell efficiency greatly. Also hydrogen was found to play a critical role in controlling the crystallinity. Instead of employing conventional plasma deposition techniques, this work focused on using catalytic chemical vapor deposition (Cat-CVD) to study the effect of hydrogen dilution and the filament-to-substrate distance on the crystallinity, deposition rate, microstructure factor and electrical property of the μc-Si:H film. We found that the substrate material and structure can affect the crystallinity of the μc-Si:H film and the incubation effect. Comparing bare glass, TCO-coated glass, a-Si:H-coated glass and μc-Si:H-coated glass, the microcrystalline phase grows the fastest onto μc-Si:H surface, but the slowest onto a-Si:H surface. Surprisingly, the template effect lasted for more than a thousand atomic layers of silicon.