Identification of atomic steps at AlSb/GaAs hetero-epitaxial interface using geometric phase method by high-resolution electron microscopy

Geometric phase analysis (GPA) is applied to determining the strain fields in AlSb/GaAs hetero-epitaxial film from high-resolution electron microscopy (HREM) images. The misfit dislocations along the hetero-interface are shown to be predominantly 90° Lomer dislocations. The epitaxial film is almost fully relaxed by a high density of misfit dislocations. The 90° Lomer dislocations are assumed to be formed by either recombination of two 60° mixed misfit dislocations through a glide and climb process or direct nucleation at the interface. The atomic steps (ASs) are visualized in the strain map, providing a new method for identifying the ASs at the interface.