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• Photonics Research
• Vol. 9, Issue 10, 10001907 (2021)
Long Guo1、2, Ke Jiang1、2、4、*, Xiaojuan Sun1、2, Zihui Zhang1、3, Jianwei Ben1、2, Yuping Jia1、2, Yong Wang1、2, and Dabing Li1、2、5、*
Author Affiliations
• 1State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
• 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
• 3Key Laboratory of Electronic Materials and Devices of Tianjin, School of Electronics and Information Engineering, Hebei University of Technology, Tianjin 300401, China
• 4e-mail: jiangke@ciomp.ac.cn
• 5e-mail: lidb@ciomp.ac.cn
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Abstract

AlGaN solar-blind ultraviolet (SBUV) detectors have potential application in fire monitoring, corona discharge monitoring, or biological imaging. With the promotion of application requirements, there is an urgent demand for developing a high-performance vertical detector that can work at low bias or even zero bias. In this work, we have introduced a photoconductive gain mechanism into a vertical AlGaN SBUV detector and successfully realized it in a $p-i-n$ photodiode via inserting a multiple-quantum-well (MQW) into the depletion region. The MQW plays the role of trapping holes and increasing carrier lifetime due to its strong hole confinement effect and quantum confinement Stark effect. Hence, the electrons can go through the detector multiple times, inducing unipolar carrier transport multiplication. Experimentally, an AlGaN SBUV detector with a zero-bias peak responsivity of about 0.425 A/W at 233 nm is achieved, corresponding to an external quantum efficiency of 226%, indicating the existence of internal current gain. When compared with the device without MQW structure, the gain is estimated to be about $103$ in magnitude. The investigation provides an alternative and effective approach to obtain high current gain in vertical AlGaN SBUV detectors at zero bias.

1. INTRODUCTION

Ultraviolet light in the solar-blind band (200–280 nm) hardly radiates to the Earth’s surface due to the strong atmospheric absorption. Therefore, solar-blind ultraviolet (SBUV) detectors have attracted tremendous interest in the scope of fire monitoring, high-voltage equipment corona discharge monitoring, or biological imaging [15]. AlGaN material, with a tunable wide bandgap and high absorption coefficient from 3.4 to 6.2 eV, is one of the most suitable materials for SBUV detectors [6]. Moreover, AlGaN SBUV detectors have the advantage of small-size, low-power-consumption, and easy-integration over the most frequently used photomultiplier tubes that feature high vacuum, high voltage, and huge volume [79]. Although considerable progress has been made on AlGaN SBUV detectors in recent years, the performance still cannot meet the requirements of real applications because of the poor crystal quality and $p$-doping efficiency deterioration with increasing Al content [10,11]. In order to obtain optimal device performance on the platform with the current AlGaN material quality and $p$-doping efficiency, the structures have been extensively studied and finely optimized.

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Long Guo, Ke Jiang, Xiaojuan Sun, Zihui Zhang, Jianwei Ben, Yuping Jia, Yong Wang, Dabing Li. Multiple-quantum-well-induced unipolar carrier transport multiplication in AlGaN solar-blind ultraviolet photodiode[J]. Photonics Research, 2021, 9(10): 10001907