Ab initioparameterized valence force field for the structure and energetics of amorphous SiOx(0 ⩽x ⩽2) materials

Abstract

We present a modified valence force field model for the structure and energetics of amorphous silicon suboxides (a-SiO${}_{x}$, 0 \ensuremath{\leqslant} $x$ \ensuremath{\leqslant} 2). The parameters are optimized to fit the results from cluster and periodic density-functional theory (DFT) calculations of various model structures. The potential model well reproduces the DFT energetics of various $a$-SiO${}_{x}$ systems for all O:Si composition ratios. We also examine how the choice of force fields affects the atomic-level description of phase separation in a-SiO${}_{x}$ and $a$-Si/$a$-SiO${}_{2}$ interfaces using a continuous random network model-based Monte Carlo approach. The results highlight the critical role of the relative rigidity between Si and SiO${}_{2}$ matrices in determination of the structural properties of the Si/SiO${}_{2}$ composite system, such as interface bond topology, degree of phase separation, and abruptness of the interface.