Microstructure and fractal formation of annealed Ge-Au film and Ge-Au/Au bilayer films

The as-deposited and annealed Ge-Au film and Ge-Au/Au bilayer films have been observed by transmission electron microscopy. The bilayer with a composition of Ge-5at%Au film is amorphous, while the Ge-22at%Au film is polycrystalline. Higher concentration of Au raises the structural heterogeneity and instability. Fractals can be observed in the Ge-5at%Au/Au bilayer samples annealed at 60-100°C. The difference of the fractal patterns generated from Ge-Au/Au and a-Ge/Au films can be attributed to the higher heterogeneity and instability in Ge-Au/Au bilayers.