Influence of deposition parameters on the properties of boron-doped amorphous silicon-carbide films

Abstract

The optoelectronic properties of p-type a-Si_1-xC_x:H deposited by glow-discharge decomposition have been studied at different deposition temperatures and with varying methane concentration. The optical band gap is found to increase at lower temperatures and with higher methane concentrations. Infrared transmittance spectra reveal that the increase is due to carbon and/or hydrogen incorporation. Electron-spin-resonance spectra have been analyzed to show that the dangling bond density increases with carbon content. Low-temperature deposited films are found to posess a large (~10¹⁸ cm^-3) trapped hole density, indicating a broad valence band tail. It has been found that for a band gap of about 2 eV the optoelectronic properties are similar for low- and high-temperature deposited samples.