Highly transparent and conductive p-type microcrystalline silicon carbide window layers for thin film silicon solar cells

Abstract

Transparent and conductive microcrystalline silicon carbide (μc-SiC:H) thin films are an excellent window layer for thin film solar cells. For amorphous silicon based solar cells, p-type conductive μc-SiC:H window layers were deposited by the hot-wire chemical vapor deposition (HWCVD) technique. Monomethylsilane (MMS) highly diluted in hydrogen was used as the SiC source in favor of SiC deposition in a stoichiometric form. Aluminum (Al) introduced from Trimethylaluminum (TMAl) was used as the p-type dopant. In this report, the optoelectronic properties of p-type μc-SiC:H thin films prepared with different deposition pressure and filament temperature were investigated. By managing the deposition parameters, materials with optical gap E04 ranging from 2.0 eV to 2.8 eV and dark conductivity ranging from 10-5 S/cm to 0.1 S/cm were prepared. Such p-type μc-SiC:H thin films were applied as the window layer in amorphous silicon thin film silicon solar cells. Taking advantage of the high transparency of μc-SiC:H window layer, improved quantum efficiency was obtained at the short wavelength below 500 nm.