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

Abstract

Wide-bandgap semiconducting gallium oxide (Ga2O3) possesses significant potential in 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 contacts. The atomic transmission electron microscopy (TEM) images proves that the Bi-Ga2O3 interface is an ordered single-crystal heterojunction with few interface defects. Compared with traditional two-electrode devices, interdigital-electrode devices demonstrate 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 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.