Oxygen vacancies and donor impurities in β-Ga2O3

TLDR

Hybrid‑functional calculations were used to study how oxygen vacancies and various impurities affect the electrical and optical properties of β‑Ga₂O₃. The study shows that oxygen vacancies are deep donors and cannot account for the unintentional n‑type conductivity, which instead arises from shallow donors such as silicon, hydrogen, and other substitutional impurities (Ge, Sn, F, Cl).

Abstract

Using hybrid functionals we have investigated the role of oxygen vacancies and various impurities in the electrical and optical properties of the transparent conducting oxide β-Ga2O3. We find that oxygen vacancies are deep donors, and thus cannot explain the unintentional n-type conductivity. Instead, we attribute the conductivity to common background impurities such as silicon and hydrogen. Monatomic hydrogen has low formation energies and acts as a shallow donor in both interstitial and substitutional configurations. We also explore other dopants, where substitutional forms of Si, Ge, Sn, F, and Cl are shown to behave as shallow donors.