Modeling of misfit and threading dislocations in epitaxial heterostructures

Abstract

The processes of mechanical stress relaxation in lattice-mismatched heteroepitaxial films usually proceed via misfit dislocation formation at the film/substrate interface and are typically accompanied by the generation ofa high density of threading dislocations in the bulk of the film. Threading dislocations are deleterious for a wide variety of modem electronic and optoelectronic devices. Relaxation in stressed epitaxial films also gives rise to the characteristic cross-hatch surface morphology of the growing heterostructures. This article presents a short review of recent mesoscopic models describing the evolution of dislocation structures in heteroepitaxial films. Dislocation-assisted cross-hatch formation in (001)-oriented fcc film is explained theoretically and discussed on the basis of experimental results. A specific stress relaxation mechanism via threading dislocation inclination in (0001)-oriented wurtzite crystal structure films is considered and analyzed in detail. Finally, a 'reaction-kinetics' approach to threading dislocation reduction in growing films is developed.