Energetics and metastability of the silicon vacancy in cubic SiC

TL;DR

This paper uses GW approximation calculations to accurately determine the properties of silicon vacancies in cubic SiC, providing new insights into their energetics, metastability, and photoluminescence, aligning well with experimental data.

Contribution

It introduces GW-based calculations for defect energetics in cubic SiC, improving accuracy over DFT and proposing a new interpretation of photoluminescence and annealing mechanisms.

Findings

GW calculations yield formation and transition energies matching experiments.

A new assignment for the main photoluminescence line is proposed.

Barrier energies explain thermal annealing via a minority charge mechanism.

Abstract

The silicon vacancy is a prominent intrinsic defect of cubic SiC (3C-SiC) to which much effort has been devoted so far, experimentally and theoretically. We calculate its properties using the GW approximation that does not suffer from the band gap problem. The obtained formation and transition energies deviate significantly from the usual density functional theory evaluations and now compare favorably with experiment. A new assignment for the main line of photoluminescence is then proposed. We further perform GW calculations for the saddle point of reaction paths. The resulting barrier energies explain the thermal annealing experiments thanks to an original mechanism mediated by a minority charge configuration.