Enhancement of the deposition rate of a-Si:H by introduction of an electronegative molecule into a silane discharge

We report enhancement of the deposition rate of hydrogenated amorphous silicon without powder formation and without deterioration of its optoelectronic properties by plasma chemical vapor deposition from silane and dichlorosilane gas mixtures. A linear relationship between the deposition rate and optical emission spectroscopy signal intensity was observed suggesting that the high deposition rate is due to enhancement of gas-phase processes. The rate of film growth increased with power density as well as with the ratio of dichlorosilane to silane mixture, but decreased with total flow rate. These results were interpreted as resulting for the negative ions being confined in the discharge volume by the plasma potential, resulting in a higher electron temperature. The increased electron temperature leads to a higher decomposition rate of silane in the gas phase.