High-performance solar-blind ultraviolet photodetector arrays based on two-inch ε-Ga2O3 films for imaging applications

To achieve high-quality solar-blind ultraviolet (UV) imaging applications based on ultrawide bandgap semiconductor photodetectors, it is crucial to fabricate highly uniform wafer-scale films. In this work, we demonstrate the fabrication of exceptionally uniform two-inch ϵ-Ga₂O₃ thin films on sapphire substrates using an off-axis pulsed laser deposition method. The two-inch ϵ-Ga₂O₃ films exhibit remarkable uniformity across key parameters, including thickness, crystalline quality, bandgap, and surface roughness, with an inhomogeneity ratio less than 5%. Additionally, these films are preferentially oriented along the (001) crystal plane. At 20 V bias, the individual ϵ-Ga₂O₃ photodetector demonstrates outstanding solar-blind UV photodetection performance, with a responsivity of 52.77 A W⁻¹ at 240 nm, an external quantum efficiency of 2.7 × 10⁴%, a dark current of 5.5 × 10⁻¹¹ A and a UV–visible rejection ratio of 1.2 × 10⁴. Furthermore, the 10 × 10 photodetector arrays fabricated on two-inch ϵ-Ga₂O₃ films exhibit highly uniform photodetection performance, with photocurrent deviations remaining within one order of magnitude and a maximum standard deviation of ∼8%. High-contrast optical imaging of the letters of ‘NIMTE’ is successfully achieved using the 10 × 10 photodetector arrays. This work provides valuable insights for fabricating wafer-scale uniform ϵ-Ga₂O₃ films and achieving high-quality solar-blind UV imaging applications.