Self-trapped hole and impurity-related broad luminescence in β-Ga2O3

Abstract

This work explores the luminescence properties of self-trapped holes and impurity-related acceptors using one-dimensional configuration coordinate diagrams derived from hybrid functional calculations. The photoluminescence spectrum of as-grown β-Ga2O3 typically consists of a broad band in the wavelength region from ultraviolet to green and is often dominated by an impurity independent ultraviolet band that is commonly attributed to self-trapped holes. Here, we use the self-trapped hole as a benchmark to evaluate the accuracy of the theoretical defect luminescence spectra and estimate the optical properties of MgGa, BeGa, CaGa, CdGa, ZnGa, LiGa, and NO acceptor impurities, as well as their complexes with hydrogen donors. We also explore VGa acceptors complexed with hydrogen and SiGa donor impurities. The results show that these defects can give rise to broad luminescence bands peaking in the infrared to visible part of the spectrum, making them potential candidates for the defect origin of broad luminescence bands in β-Ga2O3.