Design of a bandgap-engineered barrier-blocking HOT HgCdTe long-wavelength infrared avalanche photodiode.

The performance of high-operating-temperature (HOT) longwavelength infrared (LWIR) HgCdTe avalanche photodiodes (APDs) is significantly limited by the increasing dark current related to temperature. In this paper, a novel barrier-blocking LWIR pBp-APD structure is proposed and studied, and the results show that the dark current of pBp-APD is significantly restricted compared with conventional APD without sacrificing the gain at high temperature. Furthermore, the reduction of avalanche dark current is found to be the key points of the significant suppression of dark current. The physical essence of this reduction is revealed to be the depletion of carriers in the absorption region, and the feasibility of the improved structure is further confirmed by the analysis of its energy band and electric field distribution. In addition, the reduction of gain-normalized dark current (GNDC) does not need to sacrifice the gain. The proposed LWIR pBp-APD paves the way for development of high operation temperature infrared APDs.