Optical and electrical performance of 5 µm InAs/GaSb Type-II superlattice for NOx sensing application

Abstract We report on the optical and electrical performance of optimized InAs/GaSb type-II superlattice (T2SL). The optical quality of optimal T2SL is compared with InAs/InAsSb T2SL. Dominant photoluminescence (PL) peak at around 5.3µm at 77 K was obtained for the Ga-based samples with an intensity which is less sensitive to changes in temperature compared to the Ga-free SL. The PL peak intensity of the Ga-based T2SL with an intentional InSb layer was found to be less responsive to changes in temperature and tuned to longer wavelength suitable for NO x sensing. Current-Voltage modelling of the fabricated Photodiode demonstrates that at a temperature of 110K, generation recombination (G-R) and trap assisted tunnelling (TAT) currents dominates below and above an applied bias of ~0.2 V respectively. However, at higher operating temperature (200 -300 K), diffusion current is prevalent at low applied bias while G-R and TAT are dominant at high applied bias.