Ion Assistance Effects on the Morphology of Carbon-Nickel Composite Films Grown by Physical Vapor Deposition at Various Metal Contents

Phase separation occurring on the surface of growing films provides unique means to influence the microstructure of composite materials. Here, the influence of ion assistance on the morphology of carbon-nickel nanocomposite thin films for different metal contents is investigated. Carbon-transition metal nanocomposites are relevant in the context of solar-thermal energy conversion, fusion, fuel cells, tribology or sensing. The films were grown by dual ion beam sputtering in a temperature range of RT-300°C. The growing films were irradiated by an assisting Ar ion beam with energies ranging from 50 to 130 eV. It is found that the nickel content drastically influences the morphology of the films: while films with low Ni contents show regular self-organized structures consisting of ordered Ni nanoparticles embedded in the carbon matrix, higher Ni contents predominantly exhibit a columnar morphology. The results are discussed on the basis of the interplay of ion-induced effects and phase separation modes.
Acknowledgements: Funding by the European Union, ECEMP-Project D1, "Nanoskalige Funktionsschichten auf Kohlenstoffbasis", Projektnummer 13857 / 2379 is gratefully acknowledged.