Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: the case of oxygen vacancies in metal oxides

TL;DR

This paper employs a dielectric-dependent hybrid DFT functional to accurately model oxygen vacancies in various metal oxides, successfully reproducing experimental optical and electrical properties and providing insights into defect-related excitation mechanisms.

Contribution

The study introduces a self-consistent, material-dependent hybrid DFT approach that improves the accuracy of defect property predictions in metal oxides compared to traditional methods.

Findings

Accurately predicts charge-transition levels of oxygen vacancies.

Reproduces optical and electrical behaviors consistent with experiments.

Provides insights into defect excitation mechanisms.

Abstract

We investigate the behavior of oxygen vacancies in three different metal-oxide semiconductors (rutile and anatase TiO2, monoclinic WO3, and tetragonal ZrO2) using a recently proposed hybrid density-functional method in which the fraction of exact exchange is material-dependent but obtained ab initio in a self-consistent scheme. In particular, we calculate charge-transition levels relative to the oxygen-vacancy defect and compare computed optical and thermal excitation/emission energies with the available experimental results, shedding light on the underlying excitation mechanisms and related materials properties. We find that this novel approach is able to reproduce not only ground-state properties and band structures of perfect bulk oxide materials, but also provides results consistent with the optical and electrical behavior observed in the corresponding substoichiometric defective systems.