Inversion layer solar cells on chemically vapor-deposited polycrystalline silicon thin films

Abstract

It is demonstrated that the metal-insulator-semiconductor (MIS) inversion layer (IL) process is also suited to fabricating solar cells on fine-grained polycrystalline silicon thin films prepared by low-pressure chemical-vapor deposition (LPCVD). Plasma enhanced silicon nitride was used as dielectric to create a highly conductive inversion layer at the silicon surface. As revealed by high frequency and quasistatic C-V measurements, the insulator/semiconductor interface for fine-grained LPCVD polycrystalline silicon is similar to that for the coarse-grained Wacker Silso material. An excellent external quantum efficiency in the short wavelength region was obtained for solar cells on both materials. For the 1-cm2 solar cell on 2-Ω cm p-doped LPCVD silicon an active area efficiency of ηa=1.8% was obtained. Ways of improving these cells are suggested. A total area AM1 efficiency of 13% was achieved for coprocessed 4-cm2 MIS-IL solar cells on Wacker Silso.