High-Sensitivity and Fast-Speed UV Photodetectors Based on Asymmetric Nanoporous-GaN/Graphene Vertical Junction.

Hu, Tiangui; Zhao, Lixia; Wang, Yujing; Lin, Hailong; Xie, Shihong; Hu, Yin; Liu, Chang; Zhu, Wenkai et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

GaN-based photodetectors are strongly desirable in many advanced fields, such as space communication, environmental monitoring, <i>etc</i>. However, the slow photo-response speed in currently reported high-sensitivity GaN-based photodetectors still hinders their applications. Here, we demonstrate a high-sensitivity and fast-speed UV photodetector based on asymmetric Au/nanoporous-GaN/graphene vertical junctions. The nanoporous GaN-based vertical photodetector shows an excellent rectification ratio up to ∼10<sup>5</sup> at +4 V<b>/</b>-4 V. The photo-responsivity and specific detectivity of the device is up to 1.01 × 10<sup>4</sup> A/W and 7.84 × 10<sup>14</sup> Jones, respectively, more than three orders of magnitude higher than the control planar photodetector. With switching light on and off, the repeatable on/off current ratio of the nanoporous GaN-based vertical photodetector is ∼4.32 × 10<sup>3</sup>, which is about 1.51 × 10<sup>3</sup> times to that of the control planar device. The measured rise/decay time is 12.2 μs/14.6 μs, which is the fastest value for the high-sensitivity GaN-based photodetectors to date. These results suggest that the asymmetric Au/nanoporous-GaN/graphene structure can improve the sensitivity and the photo-response speed of GaN-based PDs simultaneously.