Type-II InAs/GaSb strained layer superlattices grown on GaSb (111)B substrate

Abstract

In this paper, the authors report on the growth of InAs/GaSb type-II strained layer superlattice (T2SL) material on (111)B GaSb substrates. Both substrate temperature and V/III beam equivalent pressure ratio were varied to optimize the crystalline and optical quality of the T2SL material. Midwave infrared (λ100% cut-off ∼ 5.6 μm at 295 K) InAs/GaSb T2SL detectors were then grown on the same substrate orientation. After detailed radiometric characterization, the authors have measured, at 295 K and 4 μm, a dark current density of 0.53 A/cm2 (at −50 mV) and a Johnson noise limited specific detectivity (D*) of 8.5 × 109 Jones, which are superior values to the state-of-the-art T2SL detectors grown on conventional GaSb (100) substrates and operating in a similar wavelength range.