Synthesis and characterization of p-type transparent conducting CuAlO2 thin film by DC sputtering

Abstract P-type transparent conducting thin films of copper aluminium oxide were prepared by DC sputtering of polycrystalline CuAlO 2 target, which was fabricated by heating a stoichiometric mixture of Cu 2 O and Al 2 O 3 at 1375 K for 24 h. Thin films of CuAlO 2 were deposited on Si (4 0 0) and glass substrates. The sputtering was performed in Ar+O 2 (40 vol.%) atmosphere and the substrate temperature was 453 K. X-ray diffraction spectra of the films showed the peaks that could be assigned with those of the crystalline CuAlO 2 . Fourier transform infrared spectra showed CuO, AlO, OCuO bonding. UV–Vis–NIR 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 3.66 and 2.1 eV, respectively. The room temperature conductivity of the film was fairly high and was of the order of 0.08 S cm −1 , while the activation energy was ∼0.26 eV. Thermoelectric power measurement indicated positive value of Seebeck coefficient and its room temperature value was +128 μV K −1 . Positive value of Hall coefficient ( R H =+16.7 cm 3 C −1 ) also confirmed p-type conductivity of the films.