Performance improvement of amorphous Ga2O3 ultraviolet photodetector by annealing under oxygen atmosphere

We have demonstrated the fast-speed and high-rejection-ratio solar-blind ultraviolet (UV) photodetectors based on amorphous Ga2O3 (a-Ga2O3) films grown by atomic layer deposition. The effect of the annealing under oxygen atmosphere on the performance of a-Ga2O3 photodetectors is investigated. By the oxygen annealing at 500 °C, the 90-10% decay time of a-Ga2O3 photodetector can be decreased to ∼150 ns, and the UV/Visible rejection ratio of the photodetector can reach as high as 2.74×105, due to the significant suppression of the visible light response. Moreover, the dark current of the 500 °C-annealed photodetector is only 9.43 pA at 10 V bias. These phenomena can be explained by the decrease in oxygen vacancy concentration of the a-Ga2O3 films after the oxygen annealing. The combination of high rejection ratios and fast operating speeds offers a viable way for facile and scalable fabrication of the oxide semiconductor solar-blind UV detectors.