The underlayer effects on the electrical resistivity of Ag thin film

The effects of AZO (Aluminium-doped Zinc Oxide) undercoats on electrical resistivity of Ag thin films have been investigated. The characteristics of Ag films in 20 nm Ag / 15 nm AZO / glass stacks have been analyzed. In the layer stacks, the AZO films were deposited with various sputtering conditions, such as applied power (0.1–1.2 kW), gas pressure (0.3–5.0 Pa) and O2 concentration of sputter gas (0–50%), and the Ag films were deposited on those AZO undercoats in a fixed condition. The combination of asymmetric 2θ and symmetric θ–2θ X-ray diffraction (XRD) measurements makes the structural characteristics concerning the preferred orientation clear, distinguishing from the degree of crystallinity. From these XRD analyses, it was found that the crystalline orientation of AZO film is affected with the deposition parameters. Especially, the preferential growth of ZnO with its (002) planes parallel to the substrate is more enhanced with increasing the applied power. Also, the AZO undercoat affects the crystalline orientation of overcoated Ag film as the highly oriented Ag films with their (111) planes parallel to the substrate are deposited on the more preferentially grown AZO undercoats. It was found that highly oriented Ag films have lower electric resistivity. The obtained results indicate that the orientation of AZO crystallites affects the initial growth of Ag crystallites and the electrical resistivity of Ag films can be controlled by the sputter condition of AZO undercoat.