Preparation of p-type transparent conducting CuAlO2 thin films by reactive DC sputtering

P-type transparent conducting thin films of copper aluminate were prepared by reactive DC sputtering of a prefabricated target having 1:1 atomic ratio of Cu and Al. Films of CuAlO2 were deposited on Si (400) and glass substrates. The sputtering was performed in Ar + O-2 (40 vol.%) atmosphere and the substrate temperature was 475 K. X-ray diffraction (XRD) spectra of the films showed the peaks which could be assigned with those of the crystalline CuAlO2. UV-Visible spectrophotometric measurement showed high transparency of the films in the visible region. Both direct and indirect band gaps were found to exist and their corresponding estimated values were 3.75 and 1.85 eV, respectively. The room temperature conductivity of the film was fairly high and was of the order of 0.22 S cm(-1) while the activation energy was similar to0.25 eV. Seebeck coefficient at room temperature gave a value of + 115 muV/K confirming the p-type conductivity. Room temperature Hall effect measurement also indicated positive value of Hall coefficient with a value R-H = 14.1 cm(3)/C. (C) 2003 Elsevier Science B.V. All rights reserved.