Atomistic analysis of the impact of alloy and well-width fluctuations on the electronic and optical properties of InGaN/GaN quantum wells

TL;DR

This study provides an atomistic analysis of how alloy and well-width fluctuations influence the electronic and optical behaviors of InGaN/GaN quantum wells, highlighting localization effects and their impact on optical broadening.

Contribution

It introduces an atomistic modeling approach that simultaneously considers well-width, alloy, strain, and Coulomb fluctuations in InGaN/GaN quantum wells, revealing localization mechanisms.

Findings

Hole wave functions are strongly localized by alloy fluctuations.

Electron wave functions are mainly localized by well-width fluctuations.

Localization leads to significant inhomogeneous broadening of optical transitions.

Abstract

We present an atomistic description of the electronic and optical properties of $\text{In}_{0.25}\text{Ga}_{0.75}$N/GaN quantum wells. Our analysis accounts for fluctuations of well width, local alloy composition, strain and built-in field fluctuations as well as Coulomb effects. We find a strong hole and much weaker electron wave function localization in InGaN random alloy quantum wells. The presented calculations show that while the electron states are mainly localized by well-width fluctuations, the holes states are already localized by random alloy fluctuations. These localization effects affect significantly the quantum well optical properties,leading to strong inhomogeneous broadening of the lowest interband transition energy. Our results are compared with experimental literature data.