Modeling Of Lwir Nbn Hgcdte Photodetector

The nBn structure with an electron barrier sandwiched by n-type cap and absorber layers was predicted to suppress the Shockley-Read-Hall (SRH) generation-recombination processes and surface leakage. The MCT nBn structure has been studied by several groups to implement high operating temperature (HOT) device. In this report, the numerical analysis of the Hg1-xCdxTe nBn device in LWIR region (x=0.225) is performed utilizing Crosslight APSYS. The detector performance characterized by dark current, photo-current and detectivity is optimized by adjusting structural parameters such as Cd component and doping of each layer under various biases. Among the parameters, the trade-off between Delta E-c and Delta E-v is most intensively affected by Cd component of the barrier which was modified carefully and accomplished firstly. Furthermore, the effect of the trap density and trap energy level on the device performance is also investigated especially according to the processing techniques. At 110K, the optimized detectivity of the LWIR MCT nBn device reaches 7.5x10(10) cmHz(1/2)/W in this report, comparable with that of the DLPH device (7.6x10(10) cmHz(1/2)/W). The novel nBn HgCdTe structure is potentially valuable in LWIR region since the controllable p-doping issue is circumvented and passivation process is simplified.