Analysis of InAs/InAsSb Superlattice Miniband Positions for a Cascade LWIR Detector

The paper presents an analysis of the miniband transitions of long- infrared (LWIR) interband cascade photodetectors (ICIP), with type-II superlattices (T2SLs), gallium-free (“Ga-free”) InAs/InAsSb (xSb ${=}0.39$ ) absorber, grown by molecular beam epitaxy (MBE) on a GaAs (001) substrate. The results collected based on the photoluminescence (PL) and spectral response (SR) measurements were combined with theoretical calculations using the ( $8\times 8$ Hamiltonian) k $\cdot $ p model for both strained and strain-free structure. The temperature dependence of HH ${_{{1}}} \rightarrow $ C1, LH ${_{{1}}} \rightarrow $ C1, SO $\rightarrow $ C1 and HH ${_{{1}}} \rightarrow $ C1 was determined. Their respective 300 K energies were 114 meV, 195 meV, 290 meV and 380 meV, respectively. Moreover, the Varshni parameters were determined. For the PL results, 85 meV was observed across the entire temperature range. Remarkably, at cryogenic temperatures additional blue-shifted 5 meV and 14 meV transitions within the energy gap (Eg) occurred, respectively.