Large-scale atomistic simulations demonstrate dominant alloy disorder effects in GaBi${}_x$As${}_{1-x}$/GaAs multiple quantum wells

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 GaBi${}_x$As${}_{1-x}$/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 inter-well coupling effect, and plays an important role in the electronic and optical properties of 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. Polarisation-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 three for single quantum wells. 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 emphasise on the need for large-scale atomistic approaches to design devices with tailored functionalities based on the novel properties of bismide materials.

17 pages, 16 figures

References in corpus (3)

• Impact of alloy disorder on the band structure of compressively strained GaBiAs
• Polarization Response in InAs Quantum Dots: Theoretical Correlation between Composition and Electronic Properties
• Valence band splitting in bulk dilute bismides

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• Tunable band-gap and isotropic light absorption from bismuth-containing GaAs core$-$shell and multi$-$shell nanowires
• Nanowire design by deep learning for energy efficient photonic technologies
• Atomistic tight binding study of quantum confined Stark effect in GaBi${}_x$As${}_{1-x}$/GaAs quantum wells