Efficient Prediction of Effective Bandgap and Optical Absorption in InAs/InAsSb Type-II Superlattices Using Localization Landscape Theory

Abstract

Ga-free InAs/InAsSb type-II superlattices (T2SLs) are promising absorber materials for mid-wave and longwave infrared (MWIR and LWIR) photodetectors, yet quantitative modeling of their optically active bandgaps and absorption remains challenging due to strain and quantum confinement effects. In this work, the Localization Landscape (LL) theory is applied to efficiently predict effective bandgaps and optical absorption in strained InAs/InAsSb superlattices without explicitly solving the Schrödinger eigenvalue problem. The LL framework is coupled with strain-induced deformation potential theory to obtain effective quantum confinement potentials, from which absorption coefficients are directly evaluated. The calculated absorption spectra are quantitatively compared with absorption coefficients extracted from experimentally measured responsivity of MWIR and LWIR photodetectors. Excellent agreement is obtained in absorption onset energies, with LLpredicted optically active bandgaps matching Schrödinger-based calculations within an RMSE of 4.829 meV, and experimental cutoff energies within 10.446 meV. These results demonstrate that the LL framework serves as a computationally efficient and physically consistent alternative to eigenstate-based solvers for modeling disordered superlattice absorbers relevant to infrared photodetector design.