Z-contrast imaging of dislocation cores at the GaAs/Si interface

The interface between silicon and epitaxial GaAs thin film grown by metalorganic chemical vapor deposition was studied using atomic-resolution Z-contrast imaging. Z-contrast imaging provides chemical composition information and allows direct interpretation of micrographs without simulation. Three different types of dislocations were identified. As expected, a dangling bond was found in the atomic structure of the 60° dislocation. One of the observed 90° dislocations had the reconstructed atomic core structure (with no dangling bonds). The core structure of the other 90° dislocation exhibited a dangling bond.