Abstract
Bismide semiconductor materials and heterostructures are considered a promising candidate for the design and implementation of photonic, thermoelectric, photovoltaic, and spintronic devices. This work presents a detailed theoretical study of the electronic and optical properties of strongly coupled /GaAs multiple quantum well (MQW) structures. Based on a systematic set of large-scale atomistic tight-binding calculations, our results reveal that the impact of atomic-scale fluctuations in alloy composition is stronger than the interwell coupling effect, and plays an important role in the electronic and optical properties of the investigated MQW structures. Independent of QW geometry parameters, alloy disorder leads to a strong confinement of charge carriers, a large broadening of the hole energies, and a red-shift in the ground-state transition wavelength. Polarization-resolved optical transition strengths exhibit a striking effect of disorder, where the inhomogeneous broadening could exceed an order of magnitude for MQWs, in comparison to a factor of about 3 for single QWs. The strong influence of alloy disorder effects persists when small variations in the size and composition of MQWs typically expected in a realistic experimental environment are considered. The presented results highlight the limited scope of continuum methods and emphasize on the need for large-scale atomistic approaches to design devices with tailored functionalities based on the novel properties of bismide materials.
- Received 22 November 2017
DOI:https://doi.org/10.1103/PhysRevMaterials.2.044602
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