Effect of Higher Silanes in Silane Plasmas on Properties of Hydrogenated Amorphous Silicon Films

The properties of hydrogenated amorphous silicon (a-Si:H) were investigated and correlated to the densities of neutral higher silane (HS) molecules in silane radio frequency (rf) glow discharge plasmas which are used to grow a-Si:H films. The suppression of defect densities at the light soaked state was observed for “device-grade” a-Si:H with a decrease in the density of HS. On the basis of the dependence of the density of HS on the deposition rate, it is suggested that deterioration of the properties of a-Si:H deposited at a high deposition rate is attributed to the increase in the number of HSs in silane plasmas.