Sampling the diffusion paths of a neutral vacancy in Silicon with quantum mechanical calculations

TL;DR

This paper uses quantum mechanical calculations to explore how neutral vacancies in silicon diffuse, identifying diffusion paths, energy barriers, and competing mechanisms, providing insights consistent with experimental data.

Contribution

It presents a first-principles approach to map vacancy diffusion paths and mechanisms in silicon, including energy barriers and competing processes.

Findings

Vacancy diffusion occurs via hops to nearest neighbors with a 0.40 eV barrier.

Reorientation and bond recombination are identified as competing mechanisms.

Diffusion pathways align with experimental observations.

Abstract

We report a first-principles study of vacancy-induced self-diffusion in crystalline silicon. Starting form a fully relaxed configuration with a neutral vacancy, we proceed to search for local diffusion paths. The diffusion of the vacancy proceeds by hops to first nearest neighbor with an energy barrier of 0.40 eV in agreement with experimental results. Competing mechanisms are identified, like the reorientation, and the recombination of dangling bonds by Wooten-Winer-Weaire process.