Ultrasensitive, Superhigh Signal-to-Noise Ratio, Self-Powered Solar-Blind Photodetector Based on n-Ga₂O₃/p-CuSCN Core–Shell Microwire Heterojunction

Abstract

Solar-blind photodetectors have captured intense attention due to their high significance in ultraviolet astronomy and biological detection. However, most of the solar-blind photodetectors have not shown extraordinary advantages in weak light signal detection because the forewarning of low-dose deep-ultraviolet radiation is so important for the human immune system. In this study, a high-performance solar-blind photodetector is constructed based on the n-Ga2O3/p-CuSCN core–shell microwire heterojunction by a simple immersion method. In comparison with the single device of the Ga2O3 and CuSCN, the heterojunction photodetector demonstrates an enhanced photoelectric performance with an ultralow dark current of 1.03 pA, high photo-to-dark current ratio of 4.14 × 104, and high rejection ratio (R 254/R 365) of 1.15 × 104 under a bias of 5 V. Excitingly, the heterostructure photodetector shows high sensitivity to the weak signal (1.5 μW/cm2) of deep ultraviolet and high-resolution detection to the subtle change of signal intensity (1.0 μW/cm2). Under the illumination with 254 nm light at 5 V, the photodetector shows a large responsivity of 13.3 mA/W, superb detectivity of 9.43 × 1011 Jones, and fast response speed with a rise time of 62 ms and decay time of 35 ms. Additionally, the photodetector can work without an external power supply and has specific solar-blind spectrum selectivity as well as excellent stability even through 1 month of storage. Such prominent photodetection, profited by the novel geometric construction and the built-in electric field originating from the p–n heterojunction, meets greatly well the “5S” requirements of the photodetector for practical application.

Enhanced performance of ZnO nanorod array/CuSCN ultraviolet photodetectors with functionalized graphene layers

“…The ZCR device has a signicantly higher responsive current than the ZC device. The signal-tonoise ratio (i.e., SNR ¼ (I l À I d )/I d , where I l is the photocurrent under 365 nm light illumination and I d is the dark current given above) 69 also increases from 2.2 Â 10 3 (ZC) to 3.6 Â 10 3 (ZCR), which is consistent with the calculation of the detectivity. Moreover, the response time is another important indicator for photodetector performance, including the rise time s r and the fall time s f , 70 as shown in Fig.…”

A Strategic Review on Gallium Oxide Based Deep‐Ultraviolet Photodetectors: Recent Progress and Future Prospects

“…i,j) Reproduced with permission. [219] Copyright 2019, American Chemical Society. Monolayer graphene/ freshly cleaved (100) 6 shows the device performance and the built-in voltage for the different gallium oxide based PDs showing self-powered behavior.…”

Current advances in solar-blind photodetection technology: using Ga2O3 and AlGaN

“…To improve the performance of PDs, Li et al suggested the combination of β-Ga 2 O 3 with hole transport materials such as inorganic copper-based hole transport materials including Cu 2 O, CuI, CuSCN, CuCrO 2 and CuGaO 2 , and organic hole transport materials such as PEDOT:PSS and spiro-MeOTAD, to form a heterojunction with β-Ga 2 O 3 . 148 The SB PD based on the n-Ga 2 O 3 /p-CuSCN core–shell microwire heterojunction demonstrated a responsivity of 13.3 mA W −1 , photo-to-dark current ratio of 4.14 × 10 4 , UV/visible rejection ratio of 1.15 × 10 4 and detectivity of 9.43 × 10 11 Jones under a bias of 5 V. 149 Further, Li et al 150 reported a self-powered PEDOT:PSS/Ga 2 O 3 hybrid heterojunction SB photodetector with a responsivity of 37.4 mA W −1 and detectivity of 9.2 × 10 12 Jones. The device also exhibited an EQE of 18.3% at 254 nm, which is attributed to the efficient separation of photogenerated electron–hole pairs caused by the built-in electric field and the large photovoltaic effect of the PEDOT:PSS/Ga 2 O 3 heterojunction.…”