Many body effects in the excitation spectrum of a defect in SiC

TL;DR

This paper investigates how electron correlations influence the optical properties of a specific defect in SiC, revealing significant effects on excitation energies and mechanisms through advanced many-body calculations.

Contribution

It provides a detailed analysis of many-body effects on defect excitations in SiC, clarifying the excitation mechanisms and the role of electron correlations.

Findings

Excitonic effects cause a 0.23 eV red shift in excitation energies.

Corrections to ionization levels depend on defect state occupation.

The study re-assigns excitation mechanisms at photo-induced resonance thresholds.

Abstract

We show that electron correlations control the photophysics of defects in SiC through both renormalization of the quasiparticle bandstructure and exciton effects. We consider the carbon vacancy, which is a well-identified defect with two possible excitation channels that involve conduction and valence band states. Corrections to the Kohn-Sham ionization levels are found to strongly depend on the occupation of the defect state. Excitonic effects introduce a red shift of 0.23 eV. The analysis unambigiously re-assigns excitation mechanism at the thresholds in photo-induced paramagnetic resonance measurements [J. Dashdorj \emph{et al.}, J. Appl. Phys. \textbf{104}, 113707 (2008)].