Atomistic studies of strain relaxation in heteroepitaxial systems

Abstract

We present a review of recent theoretical studies of different atomistic mechanisms of strainrelaxation in heteroepitaxial systems. We explore these systems in two and threedimensions using different semi-empirical interatomic potentials of Lennard-Jones andmany-body embedded atom model type. In all cases we use a universal molecular staticmethod for generating minimum energy paths for transitions from the coherent epitaxial(defect free) state to the state containing an isolated defect (localized or extended).This is followed by a systematic search for the minimum energy configuration aswell as self-organization in the case of a periodic array of islands. In this way weare able to understand many general features of the atomic mechanisms andenergetics of strain relaxation in these systems. Finally, for the special case ofPd/Cu(100) and Cu/Pd(100) heteroepitaxy we also use conventional molecular dynamicssimulation techniques to compare the compressively and tensilely strained cases. Theresults for this case are in good agreement with the existing experimental data.