Characterization of microcrystalline silicon thin film solar cells prepared by high working pressure plasma-enhanced chemical vapor deposition

Abstract

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 $\pmb{\mu \mathrm{c}-\mathrm{Si}:\mathrm{H}}$ 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 $\pmb{\mu \mathrm{c}-\mathrm{Si}:\mathrm{H}}$ 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 $(\mathrm{V}_{\mathrm{oc}})$ of cell was 0.8V, 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%, $\pmb{\mathrm{V}_{\mathrm{oc}}:0.49\mathrm{V}, \mathrm{J}_{\mathrm{sc}}:23\mathrm{mA}/\mathrm{cm}^{2}}$ , FF:64%) was able to be successfully fabricated.