New buffer layers, large band gap ternary compounds: CuAlTe₂

Abstract

After deposition, by evaporation under vacuum, of Al/Cu/Te. multilayer structures, annealing at 673 K or more for half an hour, under argon flow, allows CuAlTe2 films crystallised in the chalcopyrite structure to be obtained. The optical and electrical properties are interpreted by introducing the influence of impurity foreign phases present in the films. The optical properties are sensitive to the small Al2O3 domains randomly distributed into the CuAlTe2 polycrystalline matrix. The optical band gap is slightly increased (2.35 eV) by the presence of alumina. The conductivity measurements show that a short circuit effect can be induced by a binary CuTe degenerate phase present at the surface of the films. This effect can be suppressed by KCN etching of the samples that allows the superficial foreign phase to be dissolved.