Deep-ultraviolet n-ZnGa₂O₄/p-GaN heterojunction photodetector fabricated by pulsed laser deposition

Zinc gallium oxide (ZnGa₂O₄) has attracted considerable interest in deep-ultraviolet photodetectors, due to the ultrawide bandgap, high transmittance in the ultraviolet (UV) region, and excellent environmental stability. In this study, ZnGa₂O₄ thin films were deposited on p-GaN epi-layers using pulsed laser deposition, resulting in improved crystalline quality. The ZnGa₂O₄ film exhibited a bandgap of 4.93 eV, calculated through absorption spectra. A heterojunction photodetector (PD) was constructed, demonstrating a rectification effect, an on/off ratio of 12,697 at -5.87 V, a peak responsivity of 14.5 mA/W, and a peak detectivity of 1.14 × 10¹² Jones (262 nm, -6 V). The PD exhibited a fast response time (39 ms) and recovery time (30 ms) under 262 nm illumination. The band diagram based on the Anderson model elucidates the photoresponse and carrier transport mechanism. This work paves the way for advancing next-generation optoelectronics.