Stochastic models and Monte Carlo simulations of x-ray diffraction from relaxed epitaxial films

• Applicant: Dr. Vladimir Kaganer
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 182722588

The design of modern microelectronic devices requires combinations of materials that have distinct lattice parameters. Their epitaxial films relax, giving rise to the misfit dislocations at the interfaces and threading dislocations running from the interfaces to free surface. The x-ray diffraction is a versatile technique to study structural quality and relaxation of epitaxial films. X-ray analysis of unrelaxed (dislocation free) epitaxial films is well established and implemented in the standard software of the diffractometers. Fairly little is done, however, for the analysis of relaxed films.The goal of this proposal is to develop theoretical methods for the analysis of the x-ray diffraction patterns from epitaxial films containing correlated ensembles of misfit and threading dislocations, and dislocation loops. The Monte Carlo technique will be applied for both stochastic integration over various arrangements of dislocations with different types of correlations, and for the spatial integration over the film volume. The approaches will be developed to calculate the x-ray diffraction peaks from realistic dislocation arrangements consisting of both misfit and threading dislocations. The ways to separate contributions from different types of dislocations to the diffraction peaks will be proposed. The process of the plastic relaxation of the film and random generation of the misfit dislocations will be modeled, with the aim to obtain statistical characteristics of random dislocation distributions.

• DFG Programme: Research Grants