Rapid formation of transparent CuAlO2 thin film by thermal annealing of Cu on Al2O3

An 850-nm-thick CuAlO(2) film was formed by solid state reaction of evaporated thin film Cu on c-cut Al(2)O(3) (sapphire) at 1200 degrees C for reaction times as short as 10 min. X-ray diffractogram confirms the formation of (0 0 1) CuAlO(2), indicating oriented growth of CuAlO(2) on c-cut Al(2)O(3). Fourier transformation infra-red (FTIR) spectra showed peaks corresponding to Cu-O, Al-O and O-Cu-O bonds, confirming further the CuAlO(2) phase formation. UV-visible spectrum measurement showed high transparency of the film in the visible region with a direct band gap of 3.25 eV. The mechanism of the formation of the film is discussed. (C) 2009 Elsevier B.V. All rights reserved.