New buffer layers, large band gap ternary compounds: CuAlTe₂

¹ Université d'Oran, Laboratoire de Physique des Matériaux et Composants pour l'Électronique, B.P. 1524, El Mnaouer Oran, Algeria
² Université de Cadi Ayyad, Faculté des Sciences et Technique, B.P. 618, Guéliz, Marrakech, Morocco
³ Université de Nantes, Équipe de Physique des Solides pour l'Électronique, Groupe couche minces et Matériaux nouveaux, FSTN, 2 rue de la Houssinière, B.P. 92208, 44322 Nantes Cedex 03, France

Corresponding author: jean-christian.bernede@physique.univ-nantes.fr

Received: 10 September 1998
Revised: 4 November 1999
Accepted: 20 January 2000
Published online: 15 April 2000

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.