X-ray diffraction of epitaxial films with arbitrarily correlated dislocations: Monte Carlo calculation and experiment

Vladimir M. Kaganer, Oliver Brandt, Henning Riechert, and Karl K. Sabelfeld

Phys. Rev. B 80, 033306 – Published 31 July 2009

Abstract

We present a Monte Carlo technique to calculate the x-ray diffraction profiles from films with arbitrarily correlated dislocation distributions. Both spatial integration and the integration over several dislocation ensembles are performed simultaneously. We explicitly consider the coexistence of misfit and threading dislocation ensembles with arbitrary correlations. Using these techniques, we are able to quantitatively reproduce the experimental lineshapes for both thin (less than 100 nm) and thick (more than 1000 nm) GaN epitaxial films on SiC. Our calculations explain the ubiquitous lineshape observed for thin, highly mismatched films, with a central coherent peak accompanied by exponentially decaying diffuse scattering.