Dependence of Fractal Formation on Thickness Ratio and Annealing Time in Au/Ge Bilayer Films

The dependence of the fractal formation on the thickness ratio and the annealing time in Au/Ge bilayer films has been investigated by transmission electron microscopy. The experimental evidence indicates that the polycrystalline Ge fractal clusters with various sizes, density, and fractal dimension are formed after crystallization of amorphous Ge. It is found that the fractal formation is sensitively dependent on the thickness ratio of Au and Ge. The random successive nucleation mechanism can be used to explain the behavior of the fractal formation.