Theoretical study of strain-dependent optical absorption in Stranski-Krastanov grown InAs/InGaAs/GaAs/AlGaAs quantum dots

TL;DR

This paper presents a highly accurate theoretical analysis of optical absorption in self-assembled quantum dots, exploring how strain, composition, and size influence their optical properties with less than 1% error compared to experiments.

Contribution

It introduces optimized atomistic strain and electronic band structure models that accurately predict optical transitions in quantum dots, revealing new insights into size and composition effects.

Findings

In-plane polarized light absorption is more significant.

Absorption wavelength increases with strain layer mole fraction.

Dot diameter significantly affects absorption wavelength.

Abstract

A detailed theoretical study of the optical absorption in self-assembled quantum dots is presented in this paper. A rigorous atomistic strain model as well as a sophisticated electronic band structure model are used to ensure accurate prediction of the optical transitions in these devices . The optimized models presented in this paper are able to reproduce the experimental results with an error less than 1$\%$. The effects of incident light polarization, alloy mole fraction, quantum dot dimensions, and doping have been investigated. The in-plane polarized light absorption is more significant than the perpendicularly polarized light absorption. Increasing the mole fraction of the strain controlling layer leads to a lower energy gap and larger absorption wavelength. Surprisingly, the absorption wavelength is highly sensitive to changes in the dot diameter, but almost insensitive to changes in the dot height. This unpredicted behavior is explained by sensitivity analysis of different factors which affect the optical transition energy.