Abstract

In this paper, we demonstrate nBn InAs/InAsSb type II superlattice (T2SL) photodetectors with AlAsSb as the barrier that targets mid-wavelength infrared (MWIR) detection. To improve operating temperature and suppress dark current, a specific Sb soaking technique was employed to improve the interface abruptness of the superlattice with device passivation using a SiO₂ layer. These result in ultralow dark current density of 6.28×10⁻⁶ A/cm² and 0.31 A/cm² under −600 mV at 97 K and 297 K, respectively, which is lower than most reported InAs/InAsSb-based MWIR photodetectors. Corresponding resistance area product values of 3.20×10⁴ Ω ·cm² and 1.32 Ω ·cm² were obtained at 97 K and 297 K. A peak responsivity of 0.39 A/W with a cutoff wavelength around 5.5 µm and a peak detectivity of 2.1×10⁹ cm·Hz^1/2/W were obtained at a high operating temperature up to 237 K.

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