Resolving the band alignment of InAs/InAsSb mid-wave-infrared type-II superlattices

TL;DR

This paper combines experimental spectroscopy and numerical modeling to accurately determine the band alignment in InAs/InAsSb superlattices, improving understanding of their optical properties for infrared applications.

Contribution

It introduces a novel approach that integrates higher-order optical transition analysis with refractive-index modeling to refine band structure parameters.

Findings

Identified the origin of optical transitions in superlattices

Adjusted band offset and bandgap parameters using spectral data

Demonstrated the effectiveness of combined spectroscopy and modeling

Abstract

In this work, three InAs/InAs$_{0.65}$Sb$_{0.35}$ superlattices with different periods were investigated using photoluminescence and photoreflectance measurements and their band structure was simulated using a 14 bulk-band kp model. The structures were studied by analyzing the evolution of the spectral features in temperature and excitation power to determine the origin of optical transitions. After identifying which of these are related to the superlattice mini-bands, a rich collection of observed higher-order optical transitions was compared with refractive-index calculations. This procedure was used to adjust the parameters of the theoretical model, namely the bowing parameters of the InAsSb valence band offset and bandgap. It was also shown that the spectroscopy of the higher-order states combined with numerical modeling of the refractive index is a powerful tool for improvement of the material parameters, presenting a new approach to material studies of advanced semiconductor heterostructures.