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SRH suppressed P-G-I design for very long-wavelength infrared HgCdTe photodiodes

Authors :
Qing Li
Runzhang Xie
Fang Wang
Shuning Liu
Kun Zhang
Tao Zhang
Yue Gu
Jiaxiang Guo
Ting He
Yang Wang
Peng Wang
Yanfeng Wei
Weida Hu
Source :
Optics Express. 30:16509
Publication Year :
2022
Publisher :
Optica Publishing Group, 2022.

Abstract

The very long wavelength infrared (VLWIR, >14 µm) spectral band is an indispensable part of new-generation infrared remote sensing. Mercury cadmium telluride (HgCdTe or MCT) has shown excellent potential across the entire infrared band. However, the dark current, which is extremely sensitive to the technological level and small Cd composition, severely limits the performance of VLWIR HgCdTe photodiodes. In this study, cut-off wavelengths of up to 15 µm for HgCdTe devices with novel P-G-I (including wide bandgap p-type cap layer, grading layer and intrinsic absorption layer) designs have been reported. Compared with a device with a double-layer heterojunction (DLHJ) structure, the designed P-G-I structure successfully reduced dark current by suppressing the Shockley–Read–Hall process. Considering the balance of quantum efficiency and dark current, with the introduction of an approximately 0.8 µm thickness Cd composition grading layer, the device can achieve a high detectivity of up to 2.5×1011 cm Hz1/2 W−1. Experiments show that the P-G-I-T device has a lower dark current and a better SRH process suppressing ability than DLHJ devices, the measured detectivity achieved 8.7×1010 cm Hz1/2 W−1. According to additional research, the trap-assisted tunneling current is the primary component of the dark current. Controlling the trap concentration to as low as 1×1013 cm−3 will be continuous and meaningful work. The proposed study provides guidance for VLWIR HgCdTe photodetectors.

Details

ISSN :
10944087
Volume :
30
Database :
OpenAIRE
Journal :
Optics Express
Accession number :
edsair.doi.dedup.....df3361b37cb36a18e840c7a40e744973
Full Text :
https://doi.org/10.1364/oe.458419