AlGaN日盲紫外雪崩光电探测器暗电流研究

Research on dark current of AlGaN solar-blind ultraviolet avalanche photodetectors

为了提高AlGaN日盲紫外雪崩探测器的信噪比,降低暗电流,研制高性能日盲紫外探测器,针对AlGaN日盲紫外雪崩探测器暗电流机制进行了深入研究。首先对传统p-i-n-i-n结构雪崩探测器进行了初步研究,分别设计了GaN和AlGaN的两种雪崩探测器模型,分析了其不同暗电流特性,得到的模拟暗电流特性曲线与实验吻合。在此基础上,针对日盲紫外波段高Al组分AlGaN雪崩探测器,重点分析研究了不同异质界面的负极化电荷、p型有效掺杂以及温度等因素对暗电流的影响。在AlGaN日盲紫外雪崩探测器研究中得到的近零偏工作暗电流为2.5×10-13A,在反向138V左右发生雪崩击穿,雪崩开启电流为18.3nA左右,击穿电压温度系数约为0.05V/K,与实验及文献测试结果吻合。

In order to improve the S/N ratio,reduce the dark current and develop the solar-blind photodetectors with high performance,the dark currents of the AlGaN solar-blind ultraviolet avalanche photodetectors were studied.Firstly,the conventional p-i-n-i-n avalanche photodetectors were examined using two newly designed models of avalanche photodetectors in GaN and AlGaN.Different characteristics of dark current were analyzed and the simulation of the dark current matched the experimental data well.Based on this,the effects of the negative polarization charge at different heterogeneous interfaces,the p-type effective doping and temperature on the dark current in high Al content AlGaN solar-blind avalanche photodetectors were investigated in detail.Results show that the dark current of the AlGaN solar-blind ultraviolet avalanche photodetector is about 2.5×10-13 A near zero bias,the avalanche breakdown occurs at about 138 V in reverse and the open current is about 18.3 nA,temperature coefficient for the breakdown voltage is about 0.05 V/K,which are all consistent with the experiments and the literature results well.