Quantitative strain analysis of InAs/GaAs quantum dot materials

TL;DR

This study employs geometric phase analysis on high-resolution electron microscopy images to quantitatively examine atomic-scale strain variations and lattice distortions in InAs/GaAs quantum dot materials, revealing how dislocations alleviate mismatch-induced distortions.

Contribution

It introduces a quantitative method to analyze atomic-scale strain and lattice distortions in quantum dot materials using geometric phase analysis on electron microscopy images.

Findings

Strain varies on the atomic scale and causes tetragonal distortion.

Dislocations at the interface effectively relieve lattice mismatch distortions.

Strain extends several nanometers into the GaAs spacer layer.

Abstract

Geometric phase analysis has been applied to high resolution aberration corrected (scanning) transmission electron microscopy images of InAs/GaAs quantum dot (QD) materials. We show quantitatively how the lattice mismatch induced strain varies on the atomic scale and tetragonally distorts the lattice in a wide region that extends several nanometers into the GaAs spacer layer below and above the QDs. Finally, we show how V-shaped dislocations originating at the QD/GaAs interface efficiently remove most of the lattice mismatch induced tetragonal distortions in and around the QD.