Tight-binding study of the influence of the strain on the electronic properties of InAs/GaAs quantum dots

TL;DR

This study uses an atomistic tight-binding model to analyze how strain affects the electronic properties of InAs/GaAs quantum dots, demonstrating the method's reliability and providing insights into strain-induced effects on electronic states.

Contribution

It introduces an atomistic tight-binding approach incorporating strain effects, offering a reliable alternative to pseudopotential methods for quantum dot electronic structure analysis.

Findings

ETB results agree well with pseudopotential calculations

Strain significantly influences bound state energies

Wave function elongation is affected by strain and dot coupling

Abstract

We present an atomistic investigation of the influence of strain on the electronic properties of quantum dots (QD's) within the empirical $s p^{3} s^{*}$ tight-binding (ETB) model with interactions up to 2nd nearest neighbors and spin-orbit coupling. Results for the model system of capped pyramid-shaped InAs QD's in GaAs, with supercells containing $10^{5}$ atoms are presented and compared with previous empirical pseudopotential results. The good agreement shows that ETB is a reliable alternative for an atomistic treatment. The strain is incorporated through the atomistic valence force field model. The ETB treatment allows for the effects of bond length and bond angle deviations from the ideal InAs and GaAs zincblende structure to be selectively removed from the electronic-structure calculation, giving quantitative information on the importance of strain effects on the bound state energies and on the physical origin of the spatial elongation of the wave functions. Effects of dot-dot coupling have also been examined to determine the relative weight of both strain field and wave function overlap.