Reconstruction of nuclear quadrupole interaction in (In,Ga)As/GaAs quantum dots observed by transmission electron microscopy

TL;DR

This study uses high-resolution transmission electron microscopy to analyze strain, composition, and nuclear quadrupole interactions in individual (In,Ga)As/GaAs quantum dots, providing detailed atomic-level insights.

Contribution

It introduces a method to reconstruct strain-induced electric-field gradients and nuclear quadrupole interactions at the atomic scale in quantum dots.

Findings

Reconstructed strain and composition distributions in quantum dots.

Extracted nuclear quadrupole interaction parameters from microscopy images.

Analyzed NMR spectra for different orientations of electric-field gradient and magnetic field.

Abstract

A microscopic study of the individual annealed (In,Ga)As/GaAs quantum dots is done by means of high-resolution transmission electron microscopy. The Cauchy-Green strain-tensor component distribution and the chemical composition of the (In,Ga)As alloy are extracted from the microscopy images. The image processing allows for the reconstruction of the strain-induced electric-field gradients at the individual atomic columns extracting thereby the magnitude and asymmetry parameter of the nuclear quadrupole interaction. Nuclear magnetic resonance absorption spectra are analyzed for parallel and transverse mutual orientations of the electric-field gradient and a static magnetic field.