X-ray diffraction from dislocation half-loops in epitaxial films

TL;DR

This paper uses Monte Carlo simulations to analyze how dislocation half-loops in epitaxial films affect X-ray diffraction profiles, revealing a transition from misfit to threading dislocation characteristics as film thickness increases.

Contribution

It introduces a detailed Monte Carlo model for X-ray diffraction from dislocation half-loops, comparing edge and screw dislocation contributions and studying their evolution with film thickness.

Findings

Diffraction profiles depend on the ratio of misfit to threading segment lengths.

A continuous transition from misfit to threading dislocation diffraction signatures is observed.

Contributions of edge and screw dislocations are quantitatively compared.

Abstract

X-ray diffraction from dislocation half-loops consisting of a misfit segment and two threading arms extending from it to the surface is calculated by the Monte Carlo method. The diffraction profiles and reciprocal space maps are controlled by the ratio of the total lengths of the misfit and the threading segments of the half-loops. A continuous transformation from the diffraction characteristic of misfit dislocations to that of threading dislocations with increasing thickness of an epitaxial film is studied. Diffraction from dislocations with edge and screw threading arms is considered and the contributions of both types of dislocations are compared.