Stability of surfaces in the chalcopyrite system

The stable surfaces in chalcopyrites are the polar {112} surfaces. We present an electron microscopy study of epitaxial films of different compositions. It is shown that for both CuGaSe2 and CuInSe2 the {001} surfaces form {112} facets. With increasing Cu excess the faceting is suppressed. This indicates a lower surface energy of the {001} surface than the energy of the {112} surface in the Cu-rich regime, but the {001} surface is higher in energy than the {112} surface in the Cu-poor regime. (c) 2006 American Institute of Physics.