在传统pn结红外探测器中,宽带隙阻挡层的引入可以有效降低器件暗电流。采用COMSOL软件对探测器的能带图进行仿真,结果表明,InAsSbP四元合金通过n型或p型掺杂,其能带结构能够实现价带能级的下凹或导带能级的上凸,起到阻挡空穴或电子的作用。通过理论分析和仿真计算,确定了满足阻挡层要求的InAsSbP组分。对于nBip型和pBin型红外探测器,仿真得到了阻挡层的最优厚度和最优掺杂浓度(粒子数浓度),并分析了其偏离最优值时对器件暗电流的影响。对于nBip型探测器,当阻挡层厚度为40 nm、掺杂浓度为2×10 ¹⁸ cm ^-3时,器件开关比最大;对于pBin型探测器,当阻挡层厚度为60 nm、掺杂浓度为4×10 ¹⁷ cm ^-3时,器件的开关比最大。

Introducing a blocking barrier with a wide bandgap can effectively lower the dark current of a traditional pn-junction infrared photodetector. The energy band diagrams of detectors are obtained by simulation using COMSOL software, and the simulation denotes that n- or p-type doping of the InAsSbP quaternary alloy sinks the valence band and lifts the conduction band in its energy map, thereby blocking holes or electrons. Through the theoretical analysis and simulation calculations, the compositions of InAsSbP necessary to satisfy the requirements of the blocking barrier are determined. The optimal values of the blocking-barrier thickness and doping concentration (particle-number concentration) are provided for the nBip and pBin infrared photodetectors by simulation, respectively. Further, the effects of the deviations from these optimal values on the dark currents of devices are analyzed. For the nBip detector, the maximum on-off ratio is obtained when the thickness and doping concentration are 40 nm and 2×10 18 cm -3, respectively, while for the pBin detector, the thickness and doping concentration are 60 nm and 4×10 17 cm -3, respectively.