Structural characterization of superlattice of microcrystalline silicon carbide layers for photovoltaic application

We have systematically studied a series of silicon carbide multilayer (#SiC) samples, each consisting of 30 periods of two alternating layers of microcrystalline silicon carbide (μc-SiC:H) having identical band gap of 2.2 eV but different amount of crystalline silicon volume fraction. The thickness of the μc-SiC:H layer deposited at higher power (termed as HPL) with higher degree of crystallinity was kept fixed at a value of 5 nm, while the thickness of the other μc-SiC:H layer deposited at a lower power (termed as LPL) was changed from 13 nm to 2 nm for the different samples of the series. With lowering of the LPL thickness, a decrease in the void fraction together with an improvement in the short range order within the multilayered samples was observed. By decreasing the thickness of the LPL layer up to 2 nm, the photoluminescence study indicates the formation of an intermediate band within the superlattice of μc-SiC:H. Photovoltaic properties of this superlattice layer were investigated in a p-i-n diode structure.