Atomic-scale imaging of asymmetric Lomer dislocation cores at the Ge/Si(001) heterointerface

Lomer edge dislocations formed at Ge/Si(001) hetero-interfaces have been imaged with a 1.25-MeV atomic-resolution electron microscope. The dislocation cores were primarily asymmetrical, and they were located close to the mean position of the interface, which was not structurally abrupt due to Ge–Si interdiffusion at the growth temperature of 550 °C. Structural models of the asymmetric dislocation cores could be derived directly from the experimental micrographs and image simulations were then used to validate the image interpretation.