Barrier Engineered Infrared Photodetectors Based on Type-II InAs/GaSb Strained Layer Superlattices

We present the design, growth, fabrication, and characterization of unipolar barrier photodiodes, pBiBn, based on type-II InAs/GaSb superlattice for midwave and longwave infrared detection. Design optimization of barriers using bandgap and band-offset tailorability of InAs/GaSb/AlSb superlattice system, their advantages and evolution of heterostructure designs are discussed for both the regimes. Dark current densities of 1.6 × 10^-7 and 1.42 × 10^-5 A/cm² are measured at 77 K for midwave and longwave detectors with cutoff wavelengths of 5 and 10 μm, respectively. Responsivities of 1.3 (QE = 38%) and 1.66 A/W (QE = 23.5%) are measured at 4.2 and 8.7 μm for the midwave and longwave, respectively, at 77 K. Shot noise limited peak detectivity of 8.9 × 10¹² and 7.7×10¹¹ cm-Hz^1/2-W^-1 are observed at -10 and -40 mV for midwave infrared and longwave infrared detectors, respectively, at 77 K.