Properties of misfit dislocations and pseudodislocations not typical for defects of homogeneous crystals

Abstract

The structural properties of SiGe/Si heterosystems with a stepped interface obtained by the deflection of a surface from the (001) plane by the rotation by several degrees about the [110] axis are studied. Dislocation-free systems and systems containing misf it dislocations (MDs) are investigated. The model of pseudodislocations describing the mutual rotation of (001) crystallographic planes of the film and substrate is proposed. The pseudodislocations are the elastically strained interface steps, and the magnitude of their effective Burgers vector is determined by the step height and lattice’s mismatch parameter. Long-range normal and shear stress fields in the epitaxial film are considered for the systems containing dislocations. The ambiguity of the value of the MDs Burgers vector is discussed. The mechanism for a small angle boundary formation under MDs introduction into the vicinal interface is proposed. The expression is obtained allowing one to calculate the fractions of MDs glide in the 111 planes inclined to the interface at the maximum and minimum angles based on the parameters determined from X-ray diffraction reflection curves.