【Epitaxy Papers】Hydrogen-assisted removal of oxygen vacancies in β-Ga₂O₃

      Researchers from the Henan Normal University have published a dissertation titled " Hydrogen-assisted removal of oxygen vacancies in β-Ga₂O₃" in Applied Physics Letters.

Abstract

      Oxygen vacancies (V_O) are intrinsic defects in β-Ga₂O₃ that significantly impact its device performance. These vacancies can donate electrons to the conduction band, leading to unintentional n-type conductivity in as-grown β-Ga₂O₃. In addition, V_O associated localized states can act as electron traps, scatter free carriers, and consequently degrade carrier mobility and overall device performance. Therefore, removing V_O is crucial for improving material properties, promoting the development of p-type β-Ga₂O₃ and optimizing device performance. Currently, traditional methods for V_O treatment, such as oxygen plasma treatment and thermal annealing, are effective but have high energy consumption, which is detrimental to carbon neutrality goals. This study presents a method for enhancing the removal of V_O via hydrogen doping. β-Ga₂O₃ thin films were grown under low-oxygen conditions using metal-organic chemical vapor deposition, followed by hydrogen pre-annealing. X-ray photoelectron spectroscopy and cathodoluminescence characterizations of films treated under different annealing conditions confirmed the effectiveness of hydrogen doping in promoting V_O elimination. Furthermore, ultraviolet photodetectors were fabricated using these films, and the analysis of their dark-state decay times provided additional evidence for reduced V_O concentrations. Theoretical calculations based on density functional theory using a revised PBE functional and the climbing image nudged elastic band method reveal that hydrogen incorporation induces charge redistribution, facilitating VO migration, thus enhancing defect control.

DOI：

https://doi.org/10.1063/5.0277345