Controlling of Avalanche Dark Carriers in Realizing Hot Single Photon Detector

HgCdTe avalanche photodiode operating at high temperature in mid-infrared emerges as an indispensable device in ultra-weak light detection. However, the dramatically increased dark current as the temperature rises imposes an insurmountable challenge to achieve high performance detectors. Here, we propose a novel structure for high-temperature operation with the introduction of a barrier in the gradient-doped absorption layer. This forms dual-avalanche areas for photogenerated carriers and enables the band manipulations, thus allowing the simultaneous dark current suppression and photoelectric gain enhancement. Dark carriers outside the absorption area are blocked from the multiplication layer while the rebuilt electric field with distinct gradients enhances the photogenerated carriers’ avalanche effect. Simulations of electric potentials and carrier distributions are performed to further clarify the mercury-interstitial dynamic transporting mechanism. With dedicated design of the device which can be manufactured with current material growth technology, our results reveal that dark current can be selectively controlled without the sacrifice of the photoelectric gain at hot temperature. Dark current is suppressed 10 times lower and the maximum gain up to 130 at 240K is achieved with the optimized device.