Ultrahigh Bipolar Photoresponse in a Self-Powered Ultraviolet Photodetector Based on GaN and In/Sn-Doped Ga<sub>2</sub>O<sub>3</sub> Nanowires pn junction
Wei Xu, Bei Li, Yutong Wu, Zhiyu Dong, Kun Zhang, Qingshan Wang, Shuanglong Feng, Wenqiang Lu
Abstract
Self-powered ultraviolet photodetectors with bipolar photoresponse have great potential in the fields of ultraviolet optical communication, all-optical controlled artificial synapses, high-resolution ultraviolet imaging equipment, and multiband photoelectric detection. However, the current low optoelectronic performance limits the development of such polar switching devices. Here, we construct a self-powered ultraviolet photodetector based on GaN and In/Sn-doped Ga 2 O 3 (IGTO) nanowires (NWs) pn junction structure. This unique nanowire/thin film structure allows GaN and IGTO to dominate the absorption of light at different wavelengths, resulting in a highly bipolar photoresponse. The device has a responsivity of 2.04 A/W and a normalized detectivity of 7.18 × 10 13 Jones at 254 nm and a responsivity of −2.09 A/W and a normalized detectivity of −7 × 10 13 Jones at 365 nm, both at zero bias. In addition, it has an extremely high I light / I dark ratio of 1.05 × 10 5 and ultrafast response times of 2.4/1.9 ms (at 254 nm) and 5.7/5.2 ms (at 365 nm). These excellent properties are attributed to the high specific surface area of the one-dimensional nanowire structure and the abundant voids generated by the nanowire network to enhance the absorption of light, and the p–n junction structure enables the rapid separation and transfer of photogenerated electron–hole pairs. Our findings provide a feasible strategy for high-performance wavelength-controlled polarity switching devices.