Suboxide interface in disproportionating<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>a</mml:mi></mml:math>-SiO studied by x-ray Raman scattering

Abstract

The microscopic structure of disproportionating amorphous silicon monoxide is studied by inelastic x-ray scattering at the silicon ${L}_{\text{II},\text{III}}$ edge. This material arranges into nanocrystalline regions of Si embedded in amorphous ${\text{SiO}}_{2}$ at proper annealing temperatures and in this work we demonstrate how the contribution of the suboxide interfaces between these regions can be extracted from the experimental data. The resulting near-edge spectra are analyzed in detail using a computational framework that combines molecular-dynamics simulations and density-functional theory calculations. The results indicate that the amount of silicon atoms with oxidation states between $+1$ and $+3$ is significant and depends strongly on the annealing temperature. Furthermore, the presented $s$, $p$, and $d$-type local densities of states $(\ensuremath{\ell}\text{DOS})$ demonstrate that the most significant differences are found in the $p$-type $\ensuremath{\ell}\text{DOS}$.