Dependence of fractal formation on the thickness ratio in Al/a-Ge bilayers

Abstract
Evaporated Al/a-Ge bilayer films annealed at various temperatures were investigated by transmission electron microscopy. Polycrystalline Ge fractal patterns with various sizes, densities, and fractal dimensions are formed after crystallization of a-Ge. Experiments show that the fractal formation is sensitively dependent on the thickness ratio of Al and Ge. The random successive nucleation mechanism stimulated by various temperature profiles corresponding to various thickness ratios can be used to explain the behavior of the fractal formation.