Atomistic structural description of the Si(001)/a-SiO₂ interface: The influence of different Keating-like potential parameters

We investigate the influence of force field parameterization on the atomic-level description of the interface structure between Si(001) and its amorphous oxide [Si(001)/a-SiO₂] with systematic application of continuous random network model-based Metropolis Monte Carlo (CRN-MMC) simulations. Particular emphasis is given to the nature of the potentials in both the crystalline Si and a-SiO₂ phases, especially the quantifiable relative rigidity between phases. To assess their reliability, the energetics and mechanical properties of the interface models generated from the CRN-MMC approach with different Keating-like potential parameters were compared with those calculated using density functional theory. We statistically characterized the structural parameters and interface abruptness from various potential models of varying interface O coverage ratio in terms of bond angle, ring size, and suboxide distributions; lateral Si-O-Si bridge bond interface densities; and strain energy profiles along [001]. Comparison of our simulation results and existing experimental observations shows that a sufficiently hard character of the a-SiO₂ phase parameterization is essential in generation of atomically accurate depictions of the Si(001)/a-SiO₂ interface.