Residual order within thermally grown amorphousSiO2on crystalline silicon

Abstract

The origin of x-ray diffraction peaks observed on the crystal truncation rods (CTR's) in reciprocal space for thermally grown ${\mathrm{SiO}}_{2}$ films has been investigated by large-scale atomistic simulation of silicon oxidation. Three models of ${\mathrm{SiO}}_{2}$ on Si(001), Si(111), and Si(113) were formed by introducing oxygen atoms in crystalline Si from the surfaces in an atom-by-atom manner. The ${\mathrm{SiO}}_{2}$ structures are classified as being amorphous in conventional characterizations, but retain the residual order originating from the {111} atomic planes in their parent crystals. The calculated diffraction patterns exhibit intensity peaks with Laue-function-like fringe profiles along the CTR's, at positions depending on the substrate orientations, agreeing quite well with experimental results.