# Depth, relaxation and temperature dependence of defect complexes in scanning transmission electron microscopy

## TL;DR

This paper introduces a novel STEM analysis method using Voronoi-cell integration and contrast calculations to accurately locate defect complexes in ZnO, considering effects of relaxation and temperature.

## Contribution

It presents a new 3D defect localization technique in STEM that accounts for relaxation effects and temperature dependence, enhancing accuracy over previous methods.

## Key findings

- DFT-relaxation is crucial for accurate defect position determination.
- Cooling to liquid nitrogen temperature affects neighboring columns significantly.
- Optimal acceptance angles can be determined via Michelson Contrast simulations.

## Abstract

We propose a new analysis approach for scanning transmission electron microscopy (STEM) based on the Voronoi-cell integration method to determine the three-dimensional position of the InZn and VZn defect complex in ZnO. Using state of the art simulation software and hardware, we propose using a method of calculating Michelson Contrast on simulated images to determine the optimal acceptance angles to use in an experimental setting. The effect of defect position, DFT-relaxation and cooling the sample to liquid nitrogen temperatures is investigated. DFT-relaxation is shown to be of consequence to accurately determine the three-dimensional position of the defect. Relaxation is also shown to have a significant impact on neighbouring columns at liquid nitrogen temperatures.

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Source: https://tomesphere.com/paper/1906.01471