Koichiro Niira

Thin film poly-Si solar cells using PECVD and Cat-CVD with light confinement structure by RIE

Poly-Si film prepared by PECVD method showed low ESR spin density of around 1E16/cm3 and poly-Si film prepared by Cat-CVD method showed relatively low ESR spin density of around 1E17/cm3. The cell using PECVD poly-Si film as a photo-active layer showed an intrinsic cell efficiency of 7.75%. Light confinement micro-structure was introduced to the cell applying RIE method to the glass substrate surface and enhancement of Jsc was observed.

Thin film poly-Si formation by Cat-CVD method and its application for solar cells

Abstract Poly-Si thin film which has an ESR spin density of 6.9 E16/cm3 was obtained by Cat-CVD with a deposition rate of 5.4 A/s at a relatively high deposition pressure (approx. 30 Pa) with a high hydrogen dilution (SiH4/H2=0.05). The low ESR spin density films were applied to solar cells as a photo-active layer. Although the dark V–I curves of the cell showed diode characteristics, the photo V–I curves showed very small photo-current densities, lower than 0.5 mA/cm2. A large amount of higher order silane molecules at the present high deposition pressure might be one of the causes of this small photo-current density, as well as grain boundary recombination and an incubation layer at the first stage of film deposition.