Cu-Al-O thin films are deposited on (0001) sapphire substrates by radio-frequency sputtering using an Al-Cu mosaic target. The Cu/Al atomic ratio of as-deposited Cu-Al-O films is measured to be 1.1. After deposition, the Cu-Al-O films are annealed at 600, 800, and 1000 degrees C, respectively, for 1 h in a N-2 atmosphere. The film crystal structure, electronic structure, valence band, and electrical properties are studied. The as-deposited films are amorphous and films annealed at 600 degrees C contain the crystallized CuO phase; the structure becomes crystallized CuAlO2 after annealing at 800 degrees C and 1000 degrees C. The 800 degrees C annealed film grows along the (001) plane. The crystallization decreases with the growth of the (012) and (018) planes for films annealed at 1000 degrees C. The resistivity values of the 800 degrees C and 1000 degrees C annealed films were measured as 1.07 Omega-cm and 864.01 Omega-cm, respectively. The lower resistivity of the 800 degrees C annealed film is attributed to preferred (001) growth orientation and a reduction of the energy band gap. (C) 2014 Elsevier B.V. All rights reserved.