Jia, Chun-Yang; Deng, Gong-Rong; Zhao, Peng; Zhu, Zhi-Zhen; Zhao, Jun; Zhang, Yi-Yun Source: Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves, v 43, n 2, p 166-173, April 2024; Language: Chinese;

Abstract:

The demand for high-speed response mid-wave infrared（MWIR）photodetectors（PDs）is gradually increasing in emerging fields such as free-space optical communication and frequency comb spectroscopy. The XBnn barrier infrared photodetectors greatly suppress shot noise originated from the device dark current. In this work，InAsSb/AlAsSb/ AlSb-based nBn and pBn barrier MWIR PDs were grown on GaSb substrates using molecular beam epitaxy（MBE）. The GSG PDs were fabricated to realize the radio frequency（RF）response testing. X-ray diffraction（XRD）and atomic force microscopy（AFM）results indicate that both epitaxial structures exhibit good crystal quality. The 90 μm diameter pBn PDs exhibit a lower dark current density of 0. 145 A/cm compared to the nBn PDs operating at room temperature（RT）and a reverse bias of 400 mV，which indicates the uncooled barrier PDs perform with low noise. Capacitance tests reveal that the pBn PDs，operating at zero bias，show a fully depleted barrier layer and partially depleted absorption region，while the nBn absorption region also exhibits partial depletion. RF response characterization demonstrates that the 90 μm diameter pBn PDs achieve 3 dB bandwidth of 2. 62 GHz at room temperature and under a 3 V reverse bias，which represents a 29. 7% improvement over the corresponding nBn PDs，only achieving 3 dB bandwidth of 2. 02 GHz. This signifies a preliminary achievement of uncooled barrier MWIR PDs capable of fast detection.

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