Gallium free type II InAs/InAsxSb1-x superlattice photodetectors

We report on a mid-wave infrared (λ50% cut-off ∼5.4 μm at 77 K) Ga-free Type II InAs/InAsxSb1-x (x = 0.65) superlattice detector Radiometric measurements reveal a quantum efficiency of 20% (λ = 4 μm, 77 K) with a dark current density of 2.1 × 10−4 A/cm2 (−10 mV) with spectral response observable up to 210 K. Although the Shockley-Read-Hall lifetime is expected to be longer for Ga-free superlattices, the dark current density is larger than that of conventional InAs/GaSb superlattice detectors. This is attributed to increased probability of carrier tunneling due to reduced valence and conduction band-offsets in InAs/InAsSb SL system.