背照式AlGaN/GaN基光电探测器的结构设计及性能模拟

Modeling and simulation of the back-illuminated AlGaN/GaN based photodetectors

基于扩散漂移方程,对背照式日盲紫外AlxGa1-xN异质结p-i-n光电二极管和可见盲GaN同质结吸收区和倍增区分离的雪崩光电二极管(SAM-APD)进行了建模,模拟分析了这两种探测器的光电响应特性和电学参数,结果与实测数据和文献报道数据一致性较好。计算时还考虑了材料制备和器件工艺的实际情况,分析了有关参数对器件性能的影响,这些结果对于分析器件的工作机制以及提取某些感兴趣的参数都有较好的指导意义。

The back-illuminated heterojunction AlxGa~.xN p-i-n solar-blind UV photodiode and homojunction separation-absorption-multiplication （SAM） visible-blind UV GaN-APD were modeled and simulated based on the standard drift-diffusion equation. Similar to the published data, the spectral external quantum efficiency of these photodiodes would be increasing with the i-layer thickness and bias voltage. It was found that the presence of p-A1GaN layer was critical for improving the UV rejection ratio. Moreover, the higher the effective p-doping concentration in the p-A1GaN layer was achieved, the higher the UV rejection ratio was obtained. Meanwhile, the minority carder lifetime in the p-AIGaN and n-A1GaN had a significant impact on the peak responsivity of AlxGal.~N p-i-n photodiodes. For designing a GaN SAM-APD, the combination of absorption layer thickness and multiplication layer thinckness was important to improve the eclectricai field profiles and spectral response characteristics. Considering the practical AIGaN material growth and processing condition comprehensively, some of the critical optical and electrical parameters were calculated and analyzed, which is helpful for the further device design and optimization.