Ultraviolet photodetector fabricated using laser sintering method grown Mg 0.2 Zn 0.8 O film
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Ultraviolet photodetector fabricated using laser sintering method grown Mg0.2Zn0.8O film Hongbin Wang1 · Quansheng Liu1 · Xiaochun Wang1 · Jiangbing Yan1 · He Tang1 Received: 6 May 2020 / Accepted: 29 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The Mg0.2Zn0.8O thin films were prepared on quartz substrate by laser sintering method. The effects of laser power density and irradiation time on the film structure and photoelectric properties were studied. Through XRD, SEM, and absorption spectrum test analysis, the optimal sintering technology parameters were determined. The laser power density and the laser irradiation time were determined as 53 W cm−2 and 30 s. The optimal thin film was used to prepare the MSM structure UV detector. Current–Voltage (I–V) curves were obtained under dark and ultraviolet illumination conditions, and the curves show obvious Schottky contact behavior. Ideality factor, barrier height, and saturation current density were calculated as 1.38, 0.44 eV, and 1.21*10–4 A cm−2. The detector exhibits the low dark current (4 nA at 20 V), high photocurrent-to-dark current ratio of 1 04. Correspondingly, the detectivity (D*) of 4.42 × 1012 cm Hz1/2 W−1 (Jones) and linear dynamic range of ~ 64 dB are also achieved. Above results show that the device has a larger photocurrent-to-dark current ratio and a strong ability for characterizing the signal-to-noise ratio, which makes it has the detection capacity even in weak UV environments.
1 Introduction Recently, ultraviolet detectors have aroused extensive research interest because of their wide application in missile launching detection, ultraviolet flame detection, environmental monitoring, optical communication, and other fields [1–3]. In the solar-blind ultraviolet (UV) detector, various wide bandgap semiconductor materials have been selected as UV sensitive materials, such as GaN [4–7], MgZnO [8–13], and Ga2O3 [14]. MgZnO as an ideal material for solar-blind photodetectors because of its unique properties, such as, adjustable bandgap in the solar-blind and ultraviolet visible range, high lattice matching with single crystal substrate, no pollution to environment, and relatively low film growth temperature [15]. Usually, MgZnO alloy film is formed by solid solution of ZnO and MgO and has both excellent physical and chemical stability of ZnO and MgO. In addition, the ion radius of Mg2+ (0.57A) and Zn2+ (0.60A) is very similar [16, 17], so within a certain range, Mg2+ and Zn2+ can replace each other to form MgZnO alloy. By changing * Quansheng Liu [email protected] 1
School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130012, Jilin, China
the solid solubility of Mg2+ ions in ZnO, the bandgap of MgZnO can theoretically be adjusted from 3.37 to 7.8 eV, and the corresponding wavelength range is 160–370 nm. This provides the possibility for MgZnO alloy to realize solar-blind ultraviolet detection. There are many methods for preparing MgZnO thin films
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