Research on the Ga2O3/ZnGa2O4 mixed-phase films and solar-blind photodetectors prepared directly by annealing Zn alloying Ga2O3 films

Abstract

High-Zn-content doped β-Ga₂O₃ thin films were grown on c-plane sapphire substrates using metal–organic chemical vapor deposition (MOCVD), with subsequent annealing inducing a phase transition, converting the initially single-phase material into a Ga₂O₃/ZnGa₂O₄ mixed-phase structure. Furthermore, metal–semiconductor–metal structured solar-blind photodetectors were fabricated to evaluate the ultraviolet detection capabilities of these mixed-phase films. The detector performance was significantly enhanced following annealing. At an annealing temperature of 800 °C, phase separation occurred, and the improvement in device performance became more pronounced. Devices annealed in an argon atmosphere, undergoing phase separation, exhibited superior optoelectronic performance, achieving a low dark current of 0.137 pA at a bias voltage of 10 V. At the peak wavelength, the device also demonstrated a responsivity of 2058.54 A W⁻¹, a specific detectivity of 3.21 × 10¹⁵ cm Hz^1/2 W⁻¹, and a short decay time of 2.90 ms. The exceptional performance of mixed-phase devices is likely attributed to the large number of heterojunction interfaces between Ga₂O₃ and ZnGa₂O₄. This study investigates the transition of the thin film material from a single-phase to a mixed-phase structure, analyzing the associated changes in their physical properties and detector performance. Additionally, it expands the material design framework for Ga₂O₃-based ultraviolet photodetectors and introduces a novel strategy to enhance their performance.