Photoelectric Properties of Oxygen-Doped a-Si:H Prepared by rf Sputtering

It was observed that the incorporation of a small amount of oxygen into sputtered a-Si:H films considerably enhances the photoconductivity at room temperature in comparison with that in undoped films. The mechanism of the enhancement was investigated in terms of the dangling-bond density, electron mobility and Fermi-level location. The electron lifetime was found to be roughly inversely proportional to the Si dangling-bond density. Time-of-flight experiments revealed that the electron mobility at room temperature in slightly oxygen-doped films is higher by about one order of magnitude than that in undoped films. The greatest part of the photoconductivity enhancement could be understood on the basis of an increase in the electron mobility and a reduction in the dangling-bond density.