Library of intrinsic defects in β-Ga2O3: First-principles studies

Abstract

Gallium sesquioxide (β-Ga2O3) acts as a prime candidate for next-generation power electronics, of which complex defects largely impact its electrical performances and limit its practical applications. Herein, using the first-principles method, various intrinsic defects (63 in total) are systematically investigated, including point defects and complexes, of which properties involve formation energies, transition levels, binding energies, etc. It is demonstrated that most defects are likely easier to form under Ga-rich chemical conditions, in which VO, Gai, GaO, OGa-GaO, Oi-GaO, and GaO-VGa defects are metastable to be probably detected in the experiment. Combing with deep-level transient spectroscopy (DLTS) experiments, it is preferred that OGa-VGaI(4-/6-) are related to the unknown experimental level EC-0.12–0.28 eV; Gai(+3/+1), GaOII(+3/+1) or Oi-GaOIII(+3/+1) are related to the level EC-0.74–0.82 eV; GaOIII(+3/+1), Oi-GaOI(+3/+1), Oi-GaOII(+3/+1) or OGa-GaOII(+2/0) are related to the level EC-0.95–1.1 eV; VOIII(+2/0), GaO-VGaII(+2/0) or OGa-GaOI(+2/0) are associated with level EC-1.2–1.48 eV; VOI(+2/0), OGa-VOI(1-/3-) or OGa-VOII(1-/3-) are associated with level EC-2.0–2.3 eV; OGa-VOII(+3/+2) is associated with level EC-4.37–4.38 eV. Although the uncertainty of the consistency between our theoretical predictions and experiments always remains due to the complex atomic structure and low symmetry, our findings provide a near-complete database in combination with experimental observations to define and identify defects in β-Ga2O3, which has a profound impact on understanding the radiation damage and degradation of β-Ga2O3 devices.