High Detectivity and Stability Self-Powered UV Photodetector Based on the GaN/CsAg₂I₃ Microbelt Heterojunction

In recent years, the exceptional properties of lead halide perovskites have garnered significant attention in the field of optoelectronic devices. However, the instability and toxicity of lead severely hinder their prospective commercial development. Consequently, lead-free halide perovskites and their analogues are attracting increased attention. In this work, perovskite-like CsAg2I3 microbelts were prepared in situ on the GaN substrate via a space-confined method. Furthermore, a heterojunction of CsAg2I3/GaN was fabricated and employed in the self-powered ultraviolet (UV) photodetectors (PDs) by capitalizing on its excellent band matching and wide bandgap. The presence of a built-in electric field in the heterojunction significantly suppresses the dark current, which results in a remarkably high photo-to-dark current ratio (PDCR) of approximately 3700. The low dark current additionally contributes to the reduction of shot noise, thereby enabling the detectivity of the device to reach
$10^{{12}}$
Jones. Moreover, the device possesses decent stability to UV light. These results indicate the potential application of this PD in the field of stability detection for weak UV light.