Coupled-barrier diffusion: the case of oxygen in silicon

TL;DR

This paper presents a detailed first-principles analysis of oxygen diffusion in silicon, revealing a complex coupled-barrier process that explains the observed activation energy and resolves previous conflicting theoretical results.

Contribution

It introduces a comprehensive energy hypersurface model for oxygen migration, clarifying the complex nature of the diffusion process in silicon.

Findings

Oxygen migration involves coupled barriers rather than a simple jump.

The activation energy for oxygen diffusion is approximately 2.5 eV.

Earlier models correspond to different points on the energy hypersurface.

Abstract

Oxygen migration in silicon corresponds to an apparently simple jump between neighboring bridge sites. Yet, extensive theoretical calculations have so far produced conflicting results and have failed to provide a satisfactory account of the observed $2.5$ eV activation energy. We report a comprehensive set of first-principles calculations that demonstrate that the seemingly simple oxygen jump is actually a complex process involving coupled barriers and can be properly described quantitatively in terms of an energy hypersurface with a ``saddle ridge'' and an activation energy of $\sim 2.5 $ eV. Earlier calculations correspond to different points or lines on this hypersurface.