High Detection Rate Self-Powered Ultraviolet Photodetector Based on the Mixed-Dimensional BP/n-GaN Heterojunction

Abstract

In recent years, mixed-dimensional p-n heterojunctions have exhibited promising optoelectronic properties. With the advancement of optoelectronic devices, unbiased (self-powered) photodetectors can better meet the requirements of specific scenarios. However, under zero-bias operation, the photocurrent is typically small, resulting in limited detectivity. To address this issue, this paper constructed a BP/n-GaN heterojunction photodetector through mechanical exfoliation, successfully increasing the performance of the GaN photodetector by 4-6 orders of magnitude. First, black phosphorus (BP) was synthesized via chemical vapor transport (CVT) and subsequently transferred onto an /n-GaN film to construct a BP/n-GaN heterojunction. Then, the I-V characteristics, light response and other key performances of the self-powered ultraviolet photoelectric detector based on the BP/n-GaN heterostructure were investigated. It was found that under no external bias and 365 nm illumination, the heterostructure device exhibits good rectification behavior, with a responsivity of 0.023 A/W and a detectivity is 2.9 × 10¹¹ Jones. Compared to the GaN photoelectric detector fabricated in this paper, the performance of the heterostructure device has improved by 4 orders of magnitude in terms of detection rate and response rate. Moreover, the UPS, ultraviolet-visible absorption spectroscopy tests and theoretical calculations determined the type II band alignment of the BP/n-GaN heterojunction, which can effectively separate photogenerated carriers. This study indicates that this BP/n-GaN heterojunction photodetector leverages the high carrier mobility of black phosphorus to enhance carrier transport and collection under zero bias, providing an emerging low-power UV photodetection platform relevant to nanophotonics-oriented UV sensing and communication.