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Recently, Professor Long Shibing's research group at the School of Microelectronics of the University of Science and Technology of China has made new progress in the study of gallium oxide day blind detectors. In view of the problem that the sunblind ultraviolet detector needs to face harsh environments in many application scenarios, the research group based on low-cost amorphous gallium oxide materials has realized the ultra-high sensitivity of the sunblind detector in extreme environments through defect and doping engineering. This method provides a feasible reference for the development and application of high-performance, extreme environment-resistant sunblind ultraviolet detectors. The results were published in the journal Advanced Materials.
As an indispensable part of spectral detection, the sun-blind UV photodetector plays an important role in many key application scenarios such as missile tracking, fire warning and deep space exploration. In these unique application scenarios, the sun-blind UV photodetector will inevitably face extremely harsh environments (e.g. high temperatures, high electric fields, high radiation). However, the traditional silicon-based sun-blind UV detector has low sensitivity to ultraviolet light and poor thermal stability, which is difficult to meet the needs of highly sensitive detection in harsh environments. Therefore, there is an urgent need to develop a high-performance, day-blind UV detector with high environmental tolerance. As an emerging ultra-wide bandgap semiconductor material, gallium oxide has the advantages of good thermal stability, large bandgap width, large ultraviolet absorption coefficient, and easy processing of materials, and is an ideal candidate material for day blind ultraviolet detection. At present, the sun-blind ultraviolet detector based on single crystal gallium oxide material is facing problems such as high cost, small scale and isolation difficulties. In contrast, amorphous gallium oxide has the characteristics of easy preparation, low cost and easy integration, which makes it have rich compatibility and design freedom for different application scenarios. However, the development of high-performance sun-blind ultraviolet detectors with high environmental tolerance based on amorphous gallium oxide materials also needs to solve the problems of poor material stability, high defect density, large leakage current, and obvious continuous photoconductivity effect.
Figure 1. Gallium oxide material design and performance of sun-blind UV detectors. (a) Effects of defects and doping engineering on the structure of amorphous gallium oxide, including recrystallization, nanopore formation, and nitrogen doping; (b) detection performance (response and detection rate) of devices at different annealing temperatures ;(c) I-V response curves of the designed N-900 devices at high temperatures; and (d) comparison of the performance of N-900 devices with typical high-temperature ultraviolet detectors.
In view of the above problems of amorphous gallium oxide materials, the research group successfully designed a high-performance gallium oxide blind ultraviolet detector that is resistant to extreme environments through defect and doping engineering. This defect and doping engineering, including gallium-rich gallium oxide amorphous material design and annealing process to achieve material recrystallization and doping compensation. Gallium-rich materials are the key to the device's high response current and the introduction of doping compensation, while nitrogen annealing promotes the formation of many favorable factors for optoelectronic detection, such as local crystallization, nanopores formation, defect concentration reduction, and doping compensation of amorphous materials (Figure 1a). Among the above factors, gallium-rich materials and nanopores are formed to ensure that the device has a high blind response current, while material crystallization, defect reduction and doping compensation ensure that the device has a lower dark current, so that the device output is more ideal photocurrent "top of the sky" dark current "standing" performance. GaOX-rich gaOX films with high temperature toughening of nitrogen gas enhance the stability of the material, which not only contributes to the improvement of photoelectric properties, but also helps to improve the extreme environmental resistance of the material. Through the above defects and doping engineering, a high-performance, day-blind UV detector that is resistant to extreme environments is realized. Compared with conventional amorphous gallium-rich gallium oxide devices, engineered devices have a 107-fold reduction in dark current, 102-fold (8×1015 Jones) and 102-fold (80 ms) response speed compared to conventional amorphous gallium-rich devices. At the same time, thanks to the inhibition of sub-band gap absorption, the detection rejection ratio (R254 nm/R365 nm) was increased by a factor of 105 to a record 1.8×107, showing excellent spectral selectivity of the device. In addition, the device maintains high detection performance under extreme conditions such as high temperature, high pressure, and high radiation (Figure 1c, d). In particular, the Gallium Oxide detector array designed based on this defect and doping engineering enables clear, dayblind imaging validation at high temperatures (Figure 2). The above high comprehensive performance makes the designed Gallium Oxide detector stand out in the field of ultraviolet detection. Therefore, defect and doping engineering provides a feasible reference strategy for the implementation of low-cost, ultra-sensitive, and extremely environmentally resistant blind detectors, and also provides potential implications for the engineering design of other optoelectronic devices.
Figure 2. Day-blind UV imaging demonstration. (a) Schematic diagram of the imaging system; (b) Optical photograph of the device array; (c) Light/dark current statistics of the array elements at different temperatures; (d) Static distribution of currents at different high temperatures and corresponding imaging effects.
Professor Long Shibing and Dr. Zhao Xiaolong of the School of Microelectronics of the University of Science and Technology of China are the co-corresponding authors of the paper, and doctoral student Hou Xiaohu is the first author of the paper. The research has been funded by the National Natural Science Foundation of China, the Strategic Pilot Research Program of the Chinese Academy of Sciences, the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences, the Research and Development Program of Guangdong Province in Key Areas, and the Open Project of the Key Laboratory of Microelectronic Devices and Integrated Technology of the Institute of Microelectronics, Chinese Academy of Sciences. It is also supported by the Center for Micro-nano Research and Manufacturing of the University of Science and Technology of China, the Information Science Experiment Center of the University of Science and Technology of China, the Frontier Science Center for Planetary Exploration and Forward-looking Technologies of the University of Science and Technology of China, and the Key Laboratory of Nanodevices and Applications of the Suzhou Institute of Nanotechnology and Nanobionics of the Chinese Academy of Sciences.
High-Performance Harsh-Environment-Resistant GaOX Solar-Blind Photodetectors via Defect and Doping Engineering
Xiaohu Hou, Xiaolong Zhao, Ying Zhang, Zhongfang Zhang, Yan Liu, Yuan Qin, Pengju Tan, Chen Chen, Shunjie Yu, Mengfan Ding, Guangwei Xu, Qin Hu, Shibing Long
Adv. Mater., 2021, DOI: 10.1002/adma.202106923
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The official website of the University of Science and Technology of China reports:
http://kyb.ustc.edu.cn/2021/1015/c6076a525774/page.htm
(Source: School of Microelectronics, Department of Scientific Research, University of Science and Technology of China)