Formation of a Cu-Al-Se Phase with a Long-Range Order by Molecular Beam Epitaxy

Abstract
A new phase in the Cu-Al-Se system was found on GaP substrates under growth conditions of an excess Cu vapour pressure and a growth temperature of 1073 K by use of molecular beam epitaxy. The mean composition of this film is close to the formula Cu3AlSe5, and differs considerably from the chalcopyrite structure compound CuAlSe2. We provide the first evidence of the presence of a new Cu-Al-Se phase with a long-range order.