Effect of Al components on the properties of CuAlO2 thin films deposited by RF magnetron sputtering

CuAlO2 (CAO) thin films with Al volume fraction of 1-5% were prepared by RF magnetron sputtering and were annealed at 1173 K for 4 h in the air. The microstructures, optical and hydrophily properties of the as-deposited films were studied. XRD measurement shows that all films are polycrystalline and present as Cu-Al-O phase. 3D profilometer measurement shows the minimum of surface roughness is 11.6 nm for 1% Al-CAO film, and the maximum is 38.6 nm for 5% Al-CAO film. The transmittance in the visible range decreases from 60% to 40% after the annealing process as a result of impurity and rough surface. The minimum value of average refractive index and extinction coefficient is about 1.41 and 0.031 for 1% Al-CAO film. The estimated direct band gaps of CAO films are 3.37-3.53 eV. CAO films changes from hydrophobicity to hydrophily after annealing, and water contact angle of the annealed film increases from 31.1 degrees to 70.5 degrees. (C) 2013 Elsevier B. V. All rights reserved.