Theoretical and experimental demonstration of bandgap tunability in InAs/AlSb superlattices

Based on first-principles calculations, this paper systematically investigates the bandgap tuning behavior of InAs/AlSb type-II superlattices, with the theoretical results validated by high-resolution x-ray diffraction and low-temperature photoluminescence experiments. The electronic structures of the superlattices with different period thicknesses were analyzed using the density functional theory + Revised Perdew-Burke-Ernzerhof + U method, revealing that an increase in the period thickness leads to a decrease in the bandgap, which primarily stems from the weakening of the quantum confinement effect and the spatial delocalization of carrier wave functions. Further regulation of the InAs well layer and AlSb barrier layer thicknesses demonstrates that the thickening of the well layer reduces the bandgap, whereas the thickening of the barrier layer enlarges the bandgap, and the two jointly dictate the band edge positions. The experimental measurement results are in good agreement with the theoretical calculations. Based on these findings, the band structure variations of the AlxIn1−xAsySb1−y/GaSb type-II superlattices under different periods and Al compositions were predicted, revealing that the bandgap can be continuously tuned within the mid-infrared to near-infrared range. This work provides theoretical guidance for the study of antimonide superlattice materials and the structural optimization of infrared devices.