Investigation of dislocation loops associated with As-Sb nanoclusters in GaAs

A model is developed for the elastic stress relaxation via formation of prismatic dislocation loops in a vicinity of the As-Sb nanoclusters built in GaAs matrix. The model is based on the experimental investigation of the microstructure of the As-Sb nanoclusters, which can be produced in Sb-doped GaAs films by the molecular-beam epitaxy at low temperature and subsequent anneal. A strong anisotropic mismatch between the As-Sb nanoclusters and GaAs matrix has been revealed by transmission electron microscopy. This mismatch was proven to be a reason for the formation of nanoscale dislocation loops near the nanoclusters. Our theoretical model explores the elastic properties of an inclusion with uniaxial dilatation. For such inclusions, the elastic stresses and stored energy are determined in a closed analytical form. The theoretical analysis predicts a specific nonlinear dependence of the dislocation loop diameter on the cluster diameter, which fits well the experimentally observed one. It is demonstrated that both the change in the inclusion self-energy due to diminishing dilatation and the interaction between the dislocation loop and inclusion are important in the relaxation phenomena in precipitated semiconductors. (C) 2005 American Institute of Physics.