The resistance as a function of thickness of amorphous indium oxide films exhibit deviations from Ohm's Law which is reminiscent of the behavior of 2D percolative systems. Using electron microscopy we demonstrate that this behavior is not related to conventional (geometric) percolation. Rather, the steep dependence of the resistance on thickness is shown to be consistent with the fractal nature of transport in the hoppong regime.
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Acknowledgements - We gratefully acknowledge helpful discussions with D. Shahar and M. Pollak. This research has been supported by a grant administered by the US-Israel Binational Science Foundation.