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

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.