pBn type short-wavelength infrared photodetector with an ultralow dark current and extended wavelength based on a strained InGaAs/GaAsSb superlattice

An InGaAs/GaAsSb type II superlattice (T2SL) absorber is a promising alternative material for a short-wavelength infrared (SWIR) photodetector due to the largely tunable bandgap by adjusting the thickness and material composition of InGaAs and GaAsSb in each T2SL period. We demonstrate a pBn type SWIR photodetector consisting of a strained InGaAs/GaAsSb T2SL absorber and AlGaAsSb barrier. The device presents an ultralow dark current density of 1.81 × 10^-4 A/cm² and a peak responsivity of 0.38 A/W under a reverse bias of -1 V at 300 K. The detector shows a peak detectivity of 1.62 × 10¹¹ cm·Hz^1/2/W and 4.63 × 10¹⁰ cm·Hz^1/2/W under a reverse bias of -1 V at 260 K and 300 K, respectively. Moreover, our photodetector demonstrates an extended 100% cutoff wavelength response up to 2.2 μm.