Bandgap-Engineered HgCdTe Infrared Detector Structures for Reduced Cooling Requirements
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State-of-the-art mercury cadmium telluride (HgCdTe) high performance infrared (IR) p-n heterojunction technology remains limited by intrinsic, thermal Auger generation-recombination mechanisms that necessitate strict cooling requirements and challenges related to processing technology, particularly those associated with achieving stable, controllable in-situ p-type doping in molecular beam epitaxy (MBE) grown HgCdTe. These limitations motivate the need to, firstly, increase device operating temperatures, and secondly, address material processing issues. This work investigates three alternative HgCdTe IR device architectures as potential solutions: 1) the high operating temperature (HOT) detector, 2) the nBn detector, and 3) the NBÎ½N detector. A simulation study examining the device behavior and performance metrics of the Auger-suppressed HOT structure predicts reduced noise and increased sensitivity at high operating temperatures. Moreover, a unipolar, barrier-integrated nBn structure is proposed to address the challenges with p-type doping in MBE grown HgCdTe, and predicted performance calculations motivate the experimental demonstration of HgCdTe nBn detectors. Fabricated nBn device prototypes exhibit barrier-influenced current-voltage and photoresponse characteristics. This work culminates with the novel concept of the hybrid NBÎ½N detector, which addresses both technology limitations by combining the advantages and designs of HOT and nBn detectors in a single configuration.