极化效应对AlGaN/GaN异质结p-i-n光探测器的影响

基于等效薄层电荷近似模拟表征极化电荷的作用, 通过自洽求解Poisson-Schrödinger方程以及求解载流子连续性方程, 计算并且讨论了p-AlGaN层掺杂浓度和界面极化电荷对AlGaN/GaN异质结p-i-n紫外探测器能带结构和电场分布以及光电响应的影响. 结果表明, 极化效应与p-AlGaN层掺杂浓度相互作用对探测器性能有较大影响. 其中, 在完全极化条件下, p-AlGaN层掺杂浓度越大, p-AlGaN层的耗尽区越窄, i-GaN层越容易被耗尽, 器件光电流越小. 在一定掺杂浓度条件下, 极化效应越强, p-AlGaN层的耗尽区越宽, 器件的光电流越大. 最后还分析了该结构在不同温度下的探测性能, 证明了该结构可以在高温下正常工作.

Influence of polarization effects on photoelectric response of AlGaN/GaN heterojunction p-i-n photodetectors

Based on the simulation of the polarization effect by the sheet charge layer approximately, the energy band structures and electric field distributions of AlGaN/GaN heterostructures with different doping concentrations of p-AlGaN and polarization effects are calculated by self-consistenly solving the Poisson-Schrödinger equations. The corresponding photoelectric response is calculated and discussed by solving the carriers continuity equation. The results show the interaction between the doping concentration and the polarization effect has an important influence on the performance of the p-i-n detector. Specially, under the condition of complete polarization, a high doping concentration in the p-AlGaN layer will result in a narrow depletion region in p-AlGaN layer and the i-GaN layer will be depleted easily, which corresponds to a low photocurrent. Similarly, a strong polarization will result in a wide depletion region in p-AlGaN and high photocurrent for the same doping concentration in p-AlGaN layer. Finally, the effect of temperature on the performance of the detector is calculated and analyzed. It is concluded that AlGaN/GaN heterostructure p-i-n ultraviolet detector can be used in the high temperature environment.