Optical characterization of defects in narrow-gap HgCdTe for infrared detector applications
Fang-Yu Yue(越方禹)1, Su-Yu Ma(马骕驭)1, Jin Hong(洪进)1, Ping-Xiong Yang(杨平雄)1, Cheng-Bin Jing(敬承斌)1, Ye Chen(陈晔)1, Jun-Hao Chu(褚君浩)1,2
1 Key Laboratory of Polar Materials and Devices(MOE), Department of Optoelectronics, School of Information Science Technology, East China Normal University, Shanghai 200241, China; 2 National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
Abstract Narrow-gap Hg1-xCdxTe material with a composition x of about 0.3 plays an extremely important role in mid-infrared detection applications. In this work, the optical properties of doped HgCdTe with x≈ 0.3 are reviewed, including the defects and defect levels of intrinsic VHg and the extrinsic amphoteric arsenic (As) dopants, which can act as shallow/deep donors and acceptors. The influence of the defects on the determination of band-edge electronic structure is discussed when absorption or photoluminescence spectra are considered. The inconsistency between these two optical techniques is demonstrated and analyzed by taking into account the Fermi level position as a function of composition, doping level, conductivity type, and temperature. The defect level and its evolution, especially in As-doped HgCdTe, are presented. Our results provide a systematic understanding of the mechanisms and help for optimizing annealing conditions towards p-type As-activation, and eventually for fabricating high performance mid-infrared detectors.
Fund: Project supported by the Major Program of the National Natural Science Foundation of China (Grant Nos. 61790583, 61874043, 61874045, and 61775060) and the National Key Research and Development Program, China (Grant No. 2016YFB0501604).
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