Epitaxially grown single grain boundaries in chalcopyrites

To allow a specific investigation of grain boundaries with a given orientation we have grown epitaxial grain boundaries of CuGaSe₂ by metal organic vapour phase epitaxy (MOVPE). The epitaxy on either side of the grain boundary and the Σ3 character of the grain boundary are shown by electron back-scattering diffraction (EBSD) scans. Scanning electron microscopy (SEM) micrographs show a dense grain boundary. Transmission electron microscopy (TEM) micrographs prove that the grain boundary in the film is the direct continuation of the grain boundary in the substrate. High-resolution TEM (HRTEM) shows that the grain boundary in the film is a twin as well, and thus a Σ3 boundary. This also justifies the use of a classification scheme that is derived for the cubic system for the tetragonal chalcopyrites. Thus by using a Σ3 grain boundary in the cubic GaAs substrate as a template, a Σ3 grain boundary is obtained in the tetragonal CuGaSe₂ film.