Improved response speed and detectivity of a solar-blind photodetector by contact engineering with an interdigital-electrode semimetal

Abstract

Wide-bandgap semiconducting gallium oxide (Ga₂O₃) possesses significant potential in the future market of solar-blind UV photodetection. However, the long response time of non-layered-metal contacted Ga₂O₃ photodetectors has critically impeded their commercial adoption. Here, by layered semimetal contact engineering, we devise an interdigital-electrode β-Ga₂O₃ photodetector using layered semimetal Bi as a contact. The atomic transmission electron microscopy (TEM) images prove that the Bi–Ga₂O₃ interface is an ordered single-crystal heterojunction with few interface defects. Compared with traditional two-electrode devices, the interdigital-electrode device demonstrates better performance with a short response time of 16 ms, a strong detectivity of 7.81 × 10¹³ Jones, and a high photo-dark current ratio of 8.0 × 10⁶ under the illumination of 254 nm UV light. The space-charge limited current (SCLC) model reveals that the ability of carriers to escape from trap states is enhanced in the contact region of the interdigitated-electrode structure, which improves the performance of the device.