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Photodetectors comprising of InAs/(In, Ga)Sb Type-II Superlattice (T2SL) structures demonstrate excellent performance over bulk detectors, which mainly includes tunable bandgap and controllable photo-absorption. The T2SL exhibits completely distinct properties from its constituent materials. In particular, the thickness of InAs and GaSb considered in one period of the T2SL plays a key role in determining its photoresponse. In this work, we compare two different compositions of the T2SL structure, which have similar bandgaps, in order to analyze their electronic band properties and miniband characteristics. For this, 12ML/12ML and 11ML/7ML T2SLs are examined which have a similar bandgap of 0.17eV corresponding to the wavelength of 7.2μm and the ratios of InAs-to-GaSb widths are approximately 1 and 1.5, respectively. The bandgap and density-of-states (DOS) masses are obtained by employing the k.p method within the envelope function approximation and the E-k dispersion both in the in-plane and the out-of-plane directions are analyzed. To further gain microscopic insights, we examine the carrier localization, miniband, and spectral current properties of finite T2SL structures using the Keldysh nonequilibrium Green’s function (NEGF) method. The spatial separation of electrons and holes in InAs and GaSb layers can be elucidated via the local density of states. Furthermore, a higher finite interband overlap between the first conduction band (C1) and the first heavy hole band (HH1) is observed in an 11ML/7ML T2SL which indicates a stronger absorption. Also, to predict the carrier transport in these structures, we incorporate scattering processes via the momentum dephasing model and note a lesser broadened dark current spectra in the 12ML/12ML T2SL structure. This suggests a stronger localization of carriers and as a consequence, the dark tunneling current will be indeed be suppressed in this T2SL.
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