Demonstration of ordering in semiconducting (chalcopyrite)–(zinc blende) alloys

Phase diagrams of alloys mixing the chalcopyrite crystal structure with the zinc-blende structure have been computed using a generalized antiferromagnetic Blume-Emery-Griffiths model in the tetrahedron approximation of the cluster-variational method. These phase diagrams are rich in transitions, including typically an order-disorder transition from chalcopyrite to zinc blende as a function of temperature for the undiluted chalcopyrite compound, a narrow miscibility gap between chalcopyrite and zinc-blende alloys at high temperatures, and a large miscibility gap at low temperatures. Additionally, for a range of energy parameters, novel x=1/2 stannite and other ordered phases are found. The calculated phase diagrams compare favorably with those obtained experimentally for the diluted magnetic semiconductors (${\mathrm{CuInTe}}_2$ ${)}_{1\mathrm{-}\mathit{x}}$(MnTe${)}_{2\mathit{x}}$ and (${\mathrm{AgInTe}}_2$ ${)}_{1\mathrm{-}\mathit{x}}$(MnTe${)}_{2\mathit{x}}$.