# Bunches of misfit dislocations on the onset of relaxation of Si$_{0.4}$Ge$_{0.6}$/Si(001) epitaxial films revealed by high-resolution x-ray diffraction

## TL;DR

This study uses Monte Carlo modeling of x-ray diffraction data to reveal that misfit dislocations in SiGe/Si films are bunched, causing diffraction peaks to underestimate the true relaxation level.

## Contribution

It demonstrates that dislocation bunching significantly affects x-ray diffraction analysis of epitaxial film relaxation.

## Key findings

- Dislocation bunching leads to underestimation of relaxation.
- Monte Carlo modeling accurately reproduces diffraction patterns.
- Inhomogeneous dislocation distribution is essential for understanding relaxation.

## Abstract

The experimental x-ray diffraction patterns of a Si$_{0.4}$Ge$_{0.6}$/Si(001) epitaxial film with a low density of misfit dislocations are modeled by the Monte Carlo method. It is shown that an inhomogeneous distribution of 60$^\circ$ dislocations with dislocations arranged in bunches is needed to explain the experiment correctly. As a result of the dislocation bunching, the positions of the x-ray diffraction peaks do not correspond to the average dislocation density but reveal less than a half of the actual relaxation.