Cu-Al-O thin films are deposited on (0001) sapphire substrates by radio-frequency sputtering using an
AleCu 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 C, respectively, for 1 h in a N2 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 C contain the crystallized CuO
phase; the structure becomes crystallized CuAlO2 after annealing at 800 C and 1000 C. The 800 C
annealed film grows along the (00l) plane. The crystallization decreases with the growth of the (012) and
(018) planes for films annealed at 1000 C. The resistivity values of the 800 C and 1000 C annealed films
were measured as 1.07 U-cm and 864.01 U-cm, respectively. The lower resistivity of the 800 C annealed
film is attributed to preferred (00l) growth orientation and a reduction of the energy band gap.