Atom probe composition and in situ electronic structure of epitaxial quantum dot ensembles

TL;DR

This paper combines atom probe tomography and electron microscopy to analyze the 3D composition and electronic structure of dense quantum dot ensembles, revealing significant hybridization effects overlooked in traditional isolated models.

Contribution

It introduces a method to accurately map composition and simulate electronic states in dense quantum dot arrays, highlighting ensemble hybridization effects.

Findings

High degree of hybridization between quantum dots and wetting layer

Simulated transition energies match photoluminescence data

Provides insights for quantum dot laser design

Abstract

Dense arrays of semiconductor quantum dots are currently employed in highly efficient quantum dot lasers for data communications and other applications. Traditionally, the electronic properties of such quantum nanostructures have been treated as isolated objects, with the degree of hybridization between neighboring quantum dots and the wetting layer left unexplored. Here, we use atom probe tomography and transmission electron microscopy to uncover the three-dimensional composition profile of a high-density ensemble of epitaxial InAs/GaAs quantum dots. The sub-nanometer compositional data is used to construct the 3D local band structure and simulate the electronic eigenstates within the dense quantum dot ensemble using finite element method. This in situ electronic simulation reveals a high degree of hybridization between neighboring quantum dots and the wetting layer, in stark contrast to the usual picture of isolated quantum nanostructures. The simulated transition energies are compared with low temperature photoluminescence. This work has important applications for quantum dot laser design and paves the way to engineering ensemble effects in quantum dot lasers and other quantum nanostructures.