Neutral defects in SrTiO3 studied with screened hybrid density functional theory

TL;DR

This study uses advanced hybrid density functional theory to analyze neutral defects in SrTiO3, revealing their formation energies, structural relaxations, and effects on electronic properties, including potential enhanced electron mobility.

Contribution

It provides detailed first-principles calculations of neutral defect properties in SrTiO3 using screened hybrid density functional theory, improving accuracy over previous methods.

Findings

Oxygen vacancies cause tetragonal lattice elongation.

Defect bands are accurately positioned within the band gap.

Electron effective masses are altered by defects and strain.

Abstract

The properties of neutral defects in SrTiO3 are calculated using the screened hybrid density functional of Heyd, Scuseria, and Ernzerhof. The formation energies, the crystal field splittings affecting the SrTiO3 band structure, and the relaxation geometries around each defect are discussed. Oxygen vacancies introduced in SrTiO3 are found to cause a small tetragonal elongation of the lattice along the z-axis. The resulting conduction band minimum electron effective masses deviate from the bulk values and support the proposal of enhanced electron mobility along the direction of the compressive strain. The locations of the various defect bands within the SrTiO3 gap are estimated without introducing any post hoc corrections, thus allowing a more reliable comparison with experiment.