Energetics and atomic mechanisms of dislocation nucleation in strained epitaxial layers

Article

关键词: MOLECULAR-DYNAMICS SIMULATION;    MISFIT DISLOCATIONS;    RELAXATION;    SILICON;    GROWTH;    HETEROSTRUCTURES;    INSTABILITIES;    MULTILAYERS;    SURFACES;    ALLOYS;   

DOI  :  10.1103/PhysRevB.68.155413

来源: SCIE

【 摘 要 】

We numerically study the energetics and atomic mechanisms of misfit dislocation nucleation and stress relaxation in a two-dimensional atomistic model of strained epitaxial layers on a substrate with lattice misfit. Relaxation processes from coherent to incoherent states for different transition paths are studied using interatomic potentials of Lennard-Jones type and a systematic saddle-point and transition-path search method. The method is based on a combination of a repulsive potential minimization and the nudged elastic band method. For a final state with a single misfit dislocation, the minimum-energy path and the corresponding activation barrier are obtained for different misfits and interatomic potentials. We find that the energy barrier decreases strongly with misfit. In contrast to continuous elastic theory, a strong tensile-compressive asymmetry is observed. This asymmetry can be understood as a manifestation of the asymmetry between repulsive and attractive branches of the pair potential, and it is found to depend sensitively on the form of the potential.

【 授权许可】

Free