Study of the Sb incorporation in InAs/InAsSb type-II superlattices and its influence on the band-edge profile

In this paper, we study the antimony distribution along the period of three InAs/InAsSb superlattices with different periods and Sb targets through multiple scanning transmission electron microscopy characterizations. The extracted Sb profiles appear to differ significantly from the targeted ones. We show that x-ray simulations are limited to determine accurately its distribution and we use the experimental profiles as inputs of a quantum structure simulation software to assess their influence on the determination of band offsets, bowing parameters, band alignments, and miniband widths. With this approach, the HH1 miniband width is broadened by a factor 2 at Γ point and the coupling with light-holes is enhanced in mid-wave short-period structures. This suggests that Sb inter-diffusion may play a less detrimental role than expected in the transport of the InAs/InAsSb material system for infrared photodetectors.