A study of the local electronic and atomic structure in a-Si_xC_1−x amorphous alloys using ultrasoft X-ray emission spectroscopy

Abstract

X-ray spectroscopy has been used to obtain data on the local electronic and atomic structure of a-Si_xC_1−x :H(Er) alloys produced by plasma-enhanced chemical vapor deposition (PECVD) with various relative amounts of silane and methane in the gas mixture (x=0.3–0.9). It is shown that the alloys contain silicon and carbon atoms in different coordination environments. Silicon is observed as elementary amorphous silicon and silicon carbide, and the relative amounts of these phases in the films depend on the composition of the gas mixture. Carbon atoms can form bonds with silicon in a coordination close to that found in crystalline silicon carbide, with a noticeable amount of C-H bonds also appearing. In addition, carbon can form an elementary carbon phase with various coordination numbers characteristic of graphite and diamond in the film.