Activation Energy for Oxygen Diffusion in Strained Silicon: A Hybrid Quantum-Classical Simulation Study with the Nudged Elastic Band Method

Abstract

The activation energy for oxygen diffusion in strained silicon crystal is investigated using the hybrid quantum-classical simulation scheme in combination with the nudged elastic band method. The electronic density-functional theory is applied to a local region containing the oxygen atom, while the classical inter-atomic potential, to the rest of the system. The system is stretched to three mutually perpendicular directions at a wide range of degree between -2 and 9%. We thereby find that the activation energy changes by between -0.4 and 0.2 eV depending sensitively on both direction and degree of the stretch, and that the peripheral atoms located far from the oxygen atom in the system contribute little to the change. Microscopic mechanisms of the strain-dependence of the activation energy are elucidated through combined analyses about the atomic and electronic structures.