Collapse Breakdown in Mid-Wavelength Infrared HgCdTe Avalanche Photodetector

Abstract

HgCdTe avalanche photodetector is one of the most promising candidates in capturing ultra-weak signal or even single photon in mid-wavelength infrared. However, the limited breakdown voltage and the unresolved underlying physics still lay an inevitable obstacle to achieve high-performance photodetectors. Here, for the first time we propose a collapse breakdown mechanism to thoroughly demonstrate the physics that underpins the relatively low-voltage breakdown in traditional HgCdTe positive-intrinsic-negative structures both theoretically and experimentally. Temperature-change measurement of the homemade devices is conducted to reveal the competitive behavior in the breakdown phenomenon. Below 180 K, the collapse breakdown dominates the overall device breakdown; while above 180 K, the avalanche breakdown contributes the majority to the device breakdown. With optimized structure, we achieve photoelectric gain and dark current 1700 and 10-9 A @11.3V, respectively. Remarkably, a semi-empirical formula is derived to predict the optimal prescription of doping concentrations of different layers which are capable of realizing high gain and low dark current simultaneously. Reported results in literature are included to further confirm the flexibility and universality of the mechanism. This work represents a steady step forward to recognizing the breakdown mechanism and achieving high -performance avalanche single-photon photodetectors.