Bandgap engineering with carriers blocking in long-wavelength infrared photodiodes

Abstract This document addresses the regulation of leakage current induced by composition-correlated bandgap depletion for novel bandgap gradient multilayer heterojunction (BGMH) Hg 1− x Cd x Te long-wavelength infrared (LWIR) photodiodes. The issue that the energy band barrier impedes the hole diffusion process is successfully eliminated by controlling the relative position of the electric field and the heterojunction material. Here, the technology computer-aided design (TCAD)-based device model is employed to verify the energy band distribution, and several means, including pre-etching before doping and reducing absorber-layer concentration, are proposed to optimize the device performance. Consequently, the ‘turn-on’ bias (| V to |) required for the device to transition into a diffusion-dominated is reduced from 1.2 V to less than 0.2 V. Finally, an 11.5 µ m LWIR BGMH device is utilized to confirm the proposed model and enhanced quantum efficiency from 33.2% to 70.0%, which can effectively support engineering applications.