p-Type Cu-Al-O films are successfully prepared by using radio frequency magnetron reactive co-sputtering deposition with Cu and Al metallic targets. Stoichiometric Cu/Al atomic percentage ratio has been achieved. The films show good transmittance in the range of 20-80% with an average thickness of 250 nm. The optical direct band gaps of the films are found in the range of 2.9-3.3 eV depending on the aluminum content. Blue-shift in absorption edge and optical band gap broadening effect are found with the increase of Al content in the films. (C) 2003 Elsevier B.V. All rights reserved.