Investigation of conductive and transparent Al-doped ZnO/metal dual-layer films by magnetron sputtering

Transparent conductive Al-doped ZnO (AZO)/metal (Ag or Cu) dual-layer films were deposited on glass substrates by direct current magnetron sputtering at room temperature. AZO layer thickness was about 30 nm. The thickness of Ag layer changed from 4.0 to 12.0 nm, and the thickness of Cu layer varied from 2.7 to 8.1 nm. The influence of metallic layer thickness on the structure, optical and electrical properties of dual-layer films was analyzed. Ag (111) crystalline peak was clearly observed in X-ray diffraction pattern as Ag layer thickness increases to 12.0 nm. For AZO/Cu films, besides the Cu crystalline peaks, there are copper oxide crystalline peaks. As Ag layer thickness increases from 4.0 to 12.0 nm, sheet resistance decreases from 6.37 to 3.91 Ω/sq and the average transmittance in the visible spectral region decreases from 83.7% to 72.6%, respectively. The average transmittance of AZO/Cu films with different Cu layer thicknesses is between 70.7% and 75.5%. The lowest sheet resistance is 19.2 Ω/sq when Cu layer thickness is 8.1 nm. The performance of the dual-layer films was also compared using a figure of merit. The results show that the high quality transparent and conductive films can be achieved by using AZO/metal dual-layer films.