Growth of CuGaSe₂ film by molecular beam epitaxy

Cu-Ga-Se films of different composition prepared by MBE technique were examined by reflection high energy electron diffraction, electron probe for micro analysis, X-ray diffraction and photoluminescence. The valence stoichiometry of the films is fulfilled at unity molecularity, showing that CuGaSe₂ is possible to be grown by MBE. The valence stoichiometry is almost conserved in a wide range of molecularity of the films. It is proven that the films have chalcopyrite structure over a remarkably wide range of Cu-rich composition and that the CuGaSe₂ films are epitaxially grown with the c-axis perpendicular to the (001) plane of GaAs substrate. The low temperature photoluminescence on epitaxially grown films of nearly stoichiometric and Cu-rich composition show sharp emission peaks at 1.71 eV attributed to exciton recombination, indicating that the film quality is rather high.