Structural and optical properties of CuAlTe2 thin films prepared by RF. sputtering

CuAlTe2 films have been prepared by sputtering onto water-cooled glass substrates and then heat treating under vacuum. The as-grown films exhibit p-type conductivity and a chalcopyrite structure with a preferential orientation in the ( 112) direction. The best crystallinity of the films was observed after annealing at 300 degrees C. For these films, the lattice constants were found to be: a = 5.62 angstrom and c = 12.45 angstrom. However, the approximate value of the grain size may vary bettween 60 and 120 nm from the SEM picture. The direct band-gap value at room temperature was found to be 2.45 +/- 0.02 eV for heat-treated films at 300 degrees C.