Annealing-induced performance enhancement in Bi₂O₃ film UVPD for self-powered UV image sensing

In this work, bismuth oxide (Bi₂O₃) films are deposited on the conductive substrates via radio frequency magnetron sputtering and subsequently annealed in air atmosphere to improve the crystalline quality. The effects of annealing on film morphology, structure, element composition, and optical properties are systematically investigated. Subsequently, instantaneous photoresponsive behaviors of ultraviolet photodetectors (UVPDs) constructed based on both the as-deposited and the annealed Bi₂O₃ films are evaluated and revealed to exhibit fast and sensitive response to UV illumination without any applied bias. Results suggest that the UVPD assembled with the annealed Bi₂O₃ film presents a remarkable enhancement in the photodetection capability, with the improvement reaching 2∼3 orders of magnitude for the photocurrent density, on/off ratio and detectivity. Furthermore, the UVPD developed based on the annealed Bi₂O₃ film is confirmed to consistently maintain stable and reliable photoresponse across broad light intensities, with the photocurrent density and detectivity reaching as high as 820.35 μA/cm² and 2 × 10¹¹ Jones, respectively. Additionally, based on the annealed Bi₂O₃ film, a clear imaging result of “HIT” with high contrast is achieved by the fabricated UVPD.