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Study On The Physical Mechanism Of AlGaN-Based Ultraviolet Photoconductor And Photodetector

Posted on:2022-01-18Degree:MasterType:Thesis
Country:ChinaCandidate:Z C DaiFull Text:PDF
GTID:2518306527482214Subject:Optical Engineering
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As a member of the third-generation wide-bandgap semiconductors,AlGaN has made significant progress in research and development,and UV photodetectors based on this material have also been developed unprecedentedly.Since various types of AlGaN-based UV photodetectors have different structures and working principles,their optical gain performance is also different.In order to further study the gain mechanism of related photodetectors and broaden the application range of AlGaN materials,this paper designs AlGaN-based ultraviolet detectors with different structures,including solar-blind UV avalanche photodiodes(APD)and metal-semiconductor-metal(MSM)ultraviolet Photodetectors.We studied the photoelectric characteristics and principles of the avalanche photodiodes(APD),the current transmission and photoconductivity effect of the composition high-Al AlGaN-based MSM UV photodetector,and the influence of the size of the interdigital electrode and the area of the active area on the performance of the Al0.6Ga0.4N-based MSM UV photodetector.The main research results are as follows:1.Based on the conventional p-i-n-i-n type Al0.4Ga0.6N-based solar-blind avalanche photodiode,a back-illuminated with a low-Al content p graded AlxGa1-xN layer and a high/low Al composition AlGaN multiplying layer was designed.The designed AlGaN solar-blind UV APD exhibits a 10 folds avalanche gain,which is 6.11×104,and reduced avalanche breakdown voltage compared with a conventional solar-blind UV APD.The designed solar-blind UV APD exhibits good optoelectronic characteristics,and will provide a solid theoretical basis for the future development of AlGaN-based solar-blind UV APDs.2.The photoelectric characteristics of the Al0.55Ga0.45N MSM UV photodetector with high Al composition were tested,and it was found that the Al0.55Ga0.45N MSM UV photodetector showed high photoconductivity.The current has obvious dependence on temperature and bias voltage when the bias voltage exceeds 4V.Studies have shown that the Poole-Frenkel emission mechanism is the main mode of carrier transport and changing space charge regions is the main reason for the photoconductive gain mechanisms.3.Three electrode sizes of 7(?)m×7(?)m,10(?)m×10(?)m,12(?)m×12(?)m and three active area areas of 300×300(?)m2,200×200(?)m2,100×100(?)m2 were designed to study the influence of electrode size and active area on high Al composition of the Al0.6Ga0.4N-based MSM type UV photodetector.The research results show that when the active area is the same,the breakdown voltage of the device increases with the size of the interdigital electrode,but the dark current shows the opposite trend,and the responsivity has nothing to do with the size;In the case of the same interdigital electrode,the breakdown voltage and dark current of the device increase with the increase of the active area area,but the responsivity increases with the decrease of the active area area,and the internal gain is higher.
Keywords/Search Tags:AlGaN, Ultra-violet photodetector, Solar-blind, Avalanche Photodiode, metal-semiconductor-metal
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