Annealing-dependent growth and nonlinear electrical properties of fractal Ge nanojoints based on Pd matrix

•Annealing Pd/Ge bilayer films showed fascinating fractal morphologies.•The fractal clusters consisted of Ge nanojoints.•The annealed Pd/Ge film with fractal clusters showed a nonlinear voltage–current behavior.

The Pd/Ge bilayer films with interesting fractal Ge nanojoints were successfully prepared by high-vacuum thermal evaporation techniques. It was found that Ge nanojoints embedded in Pd matrix showed fascinating fractal morphologies with average size of fractal clusters at 3.5 μm and fractal dimension at 1.77 when the films were annealed at 550 °C for 15 min. The fractal clusters formed Ge nanojoints with average size at 80 nm in width and 450 nm in length. The annealing-dependent growth model responsible for the fractal Ge nanojoints is discussed reasonably. The electrical measurements confirmed that the annealed Pd/Ge film with interesting fractal clusters showed a nonlinear voltage–current behavior.

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