Characterization of band offsets in Al$_x$In$_{1-x}$As$_y$Sb$_{1-y}$ alloys with varying Al composition

TL;DR

This study investigates the valence band offsets in Al$_x$In$_{1-x}$As$_y$Sb$_{1-y}$ alloys with varying Al composition, combining theoretical calculations and experimental measurements to understand their electronic properties for infrared photodetector applications.

Contribution

It provides the first combined theoretical and experimental analysis of valence band offsets in AlInAsSb alloys with different Al compositions.

Findings

Weak variation in valence band offsets across compositions

Valence band lacks minigaps unlike conduction band

Consistent results between tight-binding and XPS measurements

Abstract

The unprecedented wide bandgap tunability (~1 eV) of Al$_x$In$_{1-x}$As$_y$Sb$_{1-y}$ latticed-matched to GaSb enables the fabrication of photodetectors over a wide range from near-infrared to mid-infrared. In this paper, the valence band-offsets in AlxIn1-xAsySb1-y with different Al compositions are analyzed by tight-binding calculations and X-ray photoelectron spectroscopy (XPS) measurements. The observed weak variation in valence band offsets is consistent with the lack of any minigaps in the valence band, compared to the conduction band.