Enhanced Performance of HgCdTe Long-Wavelength Infrared Photodetectors With nBn Design

The performance of the long-wavelength infrared (LWIR) HgCdTe photodetectors with nBn structure is susceptible to the thickness of barrier layer and the huge mismatch of the energy band between the barrier layer and the absorption layer. Herein, a numerical simulation analysis for LWIR HgCdTe nBn device is carried out to present an enhanced performance with optimized structural and physical parameters (including thickness, doping concentration, and composition). The results provide that the valence band-offset (VBO) could be reduced by structure optimization, and could greatly improve the transport properties of photogenerated carriers. In addition, the effect of composition diffusion caused by the annealing process has also been studied to demonstrate that larger composition diffusion leads to a much higher dark current. The model and calculation results established in this article can provide important theoretical support and guidance for further researches of LWIR HgCdTe nBn devices.