STRUCTURE OF 60-DEGREES DISLOCATIONS AT THE GAAS SI INTERFACE/

High-resolution electron microscopy technique has been applied to a de tailed study of the 60 degrees dislocations at the atomic layer molecu lar-beam-epitaxial GaAs/Si interface. Their deformation fields strongl y interact with neighbor dislocations inducing irregular spacing betwe en the cores and possible dissociations. Biatomic silicon steps were o bserved at the interface, but never inside 60 degrees dislocation core s. Computer image simulation and elasticity calculations of the atomic displacement field have been used in order to determine the structure of the 60 degrees dislocation; however, due to the Eshelby effect and to interaction with some neighbor dislocations, in many cases no theo retical model could explain some observations. (C) 1996 American Insti tute of Physics.