Computational design of Si Si O2 interfaces: Stress and strain on the atomic scale

In this paper, we present results of a comparative computational study of silicon oxide interfaces with (100), (111), and (110) silicon surfaces. Density functional theory (DFT) in the local density approximation (LDA) and generalized gradient approximation with plane wave basis set and in the LDA approximation with localized numerical atomic orbitals are applied to investigate the relation between the structure and topology of chemical bonds and stress and strain effects at different Si-Si O2 interfaces, which play a crucial role in electronics materials and devices. The resulting stress energies are discussed in terms of chemical, mechanical, and electric polarization components. According to our observations, chemical and mechanical components in the interface energy are not sufficient for description of silicon suboxide systems including Si-Si O2 interfaces and the long range electrostatic interactions provide a non-negligible contribution. We uncovered computationally an effect of thermodynamic stabilization of oxygen incorporation in silicon lattice, which may have potential implications for nanoscale electronic device design. The trends in the stress energies derived from the results of the calculations are independent from the DFT approaches applied in this study.