Kinetics and mechanisms of reactive solid state dewetting in the system Ag–Ni–O Original Research Article

Thick silver films vapour deposited under ultra high vacuum onto high purity nickel foils, dewet the substrate when annealed at high temperature in air. No hole is observed in the silver film after an annealing at the same temperature in a pure argon atmosphere. SEM observations of the film surface and of cross-sections reveal that dewetting occurs when a nickel oxide layer is formed at the silver–nickel interface as a result of oxygen diffusion through the silver film [Phil. Mag. Lett. 80(2000)33]. The kinetics of the phenomenon has been studied for films 1.8 microns thick annealed at 1123 K. Four dewetting mechanisms have been identified and are described. In the case of short heat treatments (1 h at 1123 K in air) the main dewetting mechanism is observed to be the condensation at the silver–nickel oxide interface of vacancies into voids which grow towards the free surface of the silver film.