Delafossite CuAlO2 films prepared by reactive sputtering using Cu and Al targets

Composition and structure of CuAlO 2 films, deposited through the dc-reactive sputtering method using Cu and Al elemental targets and Ar-diluted oxygen gas, were controlled by the Cu and Al deposition periods and the postannealing temperature. The delafossite CuAlO 2 films were successfully prepared by the postannealing of the films with [Cu]/[Al]=1 at temperatures higher than 700 °C in the nitrogen atmosphere. In comparison with the optical absorption edge of the CuAlO 2 films, those of Cu-rich and Al-rich films sifted to the longer and shorter wavelength regions, respectively. The shifts of the optical absorption edge in the off-stoichiometric films are interpretable to be due to the additional copper oxide or aluminum oxide phase. The resistivity of the high-temperature postannealed films with p-type was in the range of 10–10 2 Ωcm.