Passivation of Oxygen Doped Hydrogenated Amorphous Silicon Coatings for Fabrication of HIT Solar Cells

The oxygen doped hydrogenated amorphous silicon (a-SiO_x:H) thin films, for fabrication of heterojunction with intrinsic thin layer (HIT) solar cells, were synthesized by hot filament chemical vapor deposition (HWCVD) on substrate of n-type Si (100).The influence of the filament current on properties of n-Si (100) substrate was investigated by minority carrier life-time measurement and with ellipsometry and Fourier transform infrared spectroscopy.The results show that depending on the filament current, the passivation of a-SiO_x:H was more effective than that of a-Si:H.For example, as the current increased, the minority carrier lifetime of n-Si (100) changed in an increase-decrease mode;passivated at an optimized current of 22.5 A, the minority carrier lifetime increased to 2530 μs and the surface recombination rate decreased to 3.6 cm/s.Moreover, the passivation did not directly relate to the relative contents of SiH and SiH₂ in a-SiO_x:H layer.