New method to characterize Sb segregation in InAs/GaSb superlattice

Sb segregation is the main contributor to the interfacial asymmetry of the InAs/GaSb superlattices. We reconstructed and quantified the Sb segregation profile in the InAs/Ga(In)Sb superlattice by a one-dimensional model using the postprocessing technique on cross-sectional STM images. The model shows a totally different profile between InAs-on-Ga(In)Sb interface and Ga(In)Sb-on-InAs interface. The asymmetric compositional profile is then added to the 8-band k.p model to investigate its effects on the band structures of the superlattice. With the Sb segregation, the effective band gap of the InAs/GaSb superlattice shifts towards a shorter wavelength. We hope that our work would provide a way to accurately predict the band structures of the InAs/GaSb superlattices by considering the nonideal interfaces.