Effect of hydrogen radicals on properties and structure of a-Si1−xCx:H films

Abstract

We investigated the effect of hydrogen radicals on properties and structure of hydrogenated amorphous silicon carbide (a-Si1−xCx:H) films by the use of a preparation system possessing both hydrogen plasma chamber and silane/methane plasma chamber. The deposition rate, the carbon content, the optical band gap and the film structure investigated with IR transmission spectroscopy remained unchanged with changes in rf power on the hydrogen plasma side. However, the refractive index increased with increasing the rf power on the hydrogen plasma side. The Urbach energy decreased from 67 to 53 meV. The photoconductivity of the films prepared with the rf power on the hydrogen plasma side of 100 W was improved to be 3×10−5 S cm−1, which was by about two orders of the magnitude larger than that without hydrogen plasma. For preparing photoconductive a-Si1−xCx:H films, it is important to generate a number of hydrogen radicals and introduce them onto the growing film surface efficiently.