Effects of Annealing on Thin Gold Films

As a part of a thin-film device study, an investigation was conducted of the conditions under which thin metal films cease to be continuous. This paper discusses the effects of annealing on thin gold films that were sandwiched between two evaporated layers of zinc sulfide. The electrical resistance of films in the 60- to 80-Å thickness range was monitored during constant-temperature anneals in a helium atmosphere. A portion of the resistance-time curve is found to follow the relationship R=R0eαt, where α depends on the temperature according to the equation α=α0e−E/kT. Electron micrographs show that the resistance increase is due to the agglomeration of the films, and it is suggested that the latter equation defines an activation energy for migration of gold atoms. A value of E∼1.8 eV is obtained for this gold-zinc sulfide system.