Nanomechanical modeling of misfit dislocations at heterointerfaces

High-resolution transmission electron microscopy (HRTEM) observations on th e atomistic structure of Nb/Al2O3 and Ag/MgO interfaces have highlighted su bstantial differences in the amplitude of the atom displacements in the cor e regions of misfit dislocations. In this publication, we present a model t hat leads to analytical expressions relating such differences in the displa cement field to differences in the bonding across the heterointerface. By m eans of this theory, we quantitatively estimate the magnitude of the shear stiffness of interatomic bonds across the interface by comparing calculated and experimentally observed atom positions at heterointerfaces. For distin ct cases the theory predicts that the misfit dislocations keep a certain "s tand-off" distance from the interface, in agreement with experimental obser vations. Measurement of the stand-off distance also leads to an estimate fo r the stiffness of the interatomic bonds across the interface.