Abstract
In this study we present a method of fabrication of nanoporous and nanostructured layers of cerium oxide on carbon substrates via radio frequency (rf) magnetron sputtering which is a technique suitable for commercial use in contrary to other techniques commonly used for preparation of nanostructured catalysts. Roughening of deposited layers is shown to be dependent on sputtering conditions and the amount of deposited material.
Optimization of these parameters results in growth of mushroom-like structures consisting of carbon base with a mantle of crystalline cerium compounds. With higher amount of deposited cerium oxide the structures start to be interconnected at their tops due to coalescence of cerium based particles forming characteristic ridged surface observable from a topographic view.
Amorphous carbon layers sputtered on a silicon wafer were used as a substrate for further analysis. Measurements of the final thicknesses of cerium oxide/amorphous carbon bi-layers point to the fact that the roughening is connected with interaction between carbon and deposited oxide and/or complex processes occurring during the sputtering leading to carbon erosion.
The performed study allows us to propose a growth model based on dynamic equilibrium between carbon etching and simultaneous deposition of cerium oxide. The influence of oxygen in the working gas on morphology of the bi-layers and the effect of rf power variation are discussed.