First-principles DFT + GW study of the Te antisite in CdTe

TL;DR

This study uses advanced first-principles methods to analyze the electronic properties of tellurium antisite defects in CdTe, revealing deep levels and optical transitions relevant for optoelectronic applications.

Contribution

It provides a detailed DFT+GW analysis of Te antisite defects in CdTe, improving accuracy over previous studies by addressing band gap errors and defect level positions.

Findings

Te antisite induces a deep (+2/0) level at 0.99 eV above valence band

Calculated zero-phonon line matches experimental luminescence around 1.1 eV

Results differ from prior studies due to improved band gap correction

Abstract

Formation energies, charge transitions levels, and quasiparticle defect states of the tellurium antisite $(\text{Te}_\text{Cd})$ in CdTe are addressed within the DFT${0.05cm}+{0.05cm}$\emph{GW} formalism. We find that $(\text{Te}_\text{Cd})$ induces a (+2/0) deep level at 0.99 eV above the valence band maximum, exhibiting a negative-U effect. Moreover, the calculated zero-phonon line for the excited state of $(\text{Te}_\text{Cd})^0$ corresponds closely with the $\sim$1.1 eV band, visible in luminescence and absorption experiments. Our results differ from previous theoretical studies, mainly due to the well-known band gap error and the incorrect position of the band edges predicted by standard DFT calculations.