  In pursuit of designing superior type-II superlattice barrier infrared
detectors, this study encompasses an exhaustive analysis of utilizing
M-structured superlattices for both the absorber and barrier layers through
proper band engineering and discusses its potential benefits over other
candidates. The electronic band properties of ideally infinite M-structures are
calculated using the eight band $k.p$ method which takes into account the
effects of both strain and microscopic interface asymmetry to primarily
estimate the bandgap and density-of-states effective mass and their variation
with respect to the thicknesses of the constituent material layers. In
contrast, for practical finite-period structures, the local density-of-states
and spectral tunneling transmission and current calculated using the Keldysh
non-equilibrium Green's function approach with the inclusion of non-coherent
scattering processes offer deep insights into the qualitative aspects of
miniband and localization engineering via structural variation. Our key results
demonstrate how to achieve a wide infrared spectral range, reduce tunneling
dark currents, induce strong interband wavefunction overlaps at the interfaces
for adequate absorption, and excellent band-tunability to facilitate unipolar
or bipolar current blocking barriers. This study, therefore, perfectly
exemplifies the utilization of 6.1 Angstrom material library to its full
potential through the demonstration of band engineering in M-structured
superlattices and sets up the right platform to possibly replace other complex
superlattice systems for targeted applications.
