Simulation of HgTe colloidal quantum dot infrared detectors based on nBn structure

HgTe colloidal quantum dot (CQD) infrared detectors have attracted significant attention due to their low cost and high performance. However, ligand engineering of the photoactive layer introduces numerous defect states, leading to considerable Shockley–Read–Hall (SRH) dark current in conventional junction-based devices. This work presents a semiconductor simulation of HgTe CQD infrared detectors based on a barrier-type nBn structure, which inherently suppresses SRH dark current compared to traditional junction designs. The energy band alignment and electric field distribution are analyzed, and the diffusion behavior of dark current is interpreted using a back-to-back junction model. The impact of different functional layer conditions on device performance was systematically analyzed. Attributed to the characteristics of electric field distribution and valence band barrier, the onset of diffusion current occurs significantly earlier in structures with p-type doped barrier layers compared to those with n-type doping. Moreover, higher n-type doping concentrations further delay the diffusion onset. In contrast, when it comes to suppressing SRH current, the effect of doping shows the opposite trend. These simulation results of HgTe colloidal quantum dot infrared detectors with a barrier-type nBn structure offer valuable theoretical guidance for device design and optimization.