High Quality Hydrogenated Amorphous Silicon Oxide Film and its Applications in Thin Film Silicon Solar Cells

Abstract

We investigated the effect of plasma power density on the film properties of intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) layer. The experimental results indicated that the defect density was increased with the increase in plasma power density. The p-i-n type thin film silicon solar cells using i-a-SiO:H films as an absorber layer were fabricated on glass substrate in order to investigate the effects of plasma power density of the i-a- SiO:H deposition and also the i-a-SiO:H thickness on the conversion efficiency (h) of the a-SiO:H based solar cell. We found that the h was improved from 6.8 to 7.3% due to the improvement in fill factor (FF) by decreasing plasma power density. By employing an optimal i-a-SiO:H layer with the thickness of 250 nm, the solar cell showed the best initial efficiency of about 7.7%. Compared with the cell using conventional i-a-Si:H absorber layer, a peak of the spectra response in the short wavelength region (400-600 nm) was shifted from 600 to 500 nm. These results showed the potential of the i-a-SiO:H films for using in top cell of multi junction solar cell in order to improve the light absorption in the short wavelength region.