Oxygen K near-edge spectra of amorphous silicon suboxides

Chemical disorder in silicon suboxides has been modelled by constructing several small atomic clusters which were used as input for multiple scattering calculations of the energy-loss near-edge structure at the oxygen It-edge. A redistribution of intensity at the O K-edge is observed as the number of second neighbour oxygen atoms is reduced, Since photoelectrons scattered by second neighbours of oxygen (at least) contribute to the spectra, O K-edge data provide valuable structural information, additional to that obtained from the Si L(23)-edge, which appears to be restricted to the local coordination shell. Comparison with the experimental O K-edge for a-SiOx, (O < x < 2), prepared by oxidation of amorphous Si, suggests that the material consists of an intimate mixture of a wide range of Si sites with varying proportions of oxygen and silicon in the first neighbour shell.