Characterization of Microcrystalline Silicon Thin Film Solar Cells Prepared by High Working Pressure Plasma-enhanced Chemical Vapor Deposition

Using the high working pressure plasma-enhanced chemical vapor deposition (HWP-PECVD) technique, the hydrogenated microcrystalline silicon (μc-Si:H) films for photovoltaic layers of thin film solar cells was investigated. The μc-Si:H films were deposited on surface textured fluorine-doped tin oxide (FTO) glass substrates at 100 Torr in a 100 MHz very high frequency (VHF) plasma of gas mixtures containing He, H₂, and SiH₄. It was found that an optimum ratio of the H₂/SiH₄ flowrate existed for growing a homogenous microcrystalline through the whole film without amorphous incubation layer. When an intrinsic μc-Si:H thin film was deposited at n-i-p single junction solar cell, the cell performances were dependent on with or without an amorphous incubation layer. With an amorphous incubation layer, the open circuit voltage (Voc) of cell was 0.8 V, which was typical cell property of hydrogenated amorphous silicon (a-Si:H). On the other hand, at the optimum ratio of the H₂/SiH₄ flow-rate, μc-Si:H single cell responding an infrared light showed the Voc of 0.49 V. Intrinsic hydrogenated microcrystalline silicon (μc-Si:H) thin film, exhibiting the photovoltaic performance (Eff: 7.2%, V_oc: 0.49V, J_sc: 23mA/cm², FF:64%) was able to be successfully fabricated.