Influence of strain on semiconductor thin film epitaxy

Abstract

Under typical growth conditions, strain levels greater than or equal to 10−4 are shown to influence thin film surface morphology and strain relaxation pathways. Misfit and threading dislocations in relaxed heterostructures produce long wavelength undulations on the surface and shallow depressions, respectively. Threading dislocation densities greater than ∼105–106 cm−2 in relaxed heterostructures must be due to increased impediments to dislocation motion, which in turn originate from the effect of the misfit dislocations on the surface morphology. Under typical growth conditions, the origin of strain-induced surface features can be identified by recognizing the length scale at which the features occur.