Ion-guided Phase Separation of Carbon-Nickel Composite Films during Ion Beam Assisted Deposition: 3D Sculpting at the Nanoscale

Ion assistance during film growth provides unique opportunities to influence the microstructure due to energy transfer and imposed directionality. During nanocomposite film growth at low temperatures, phase separation occurs at the growing film surface. Ion-assistance is a key parameter to control the surface processes during multiphase film growth, and hence the resulting nanocomposite morphology. A systematic study of ion irradiation as a pure energy and momentum transfer agent in the context of surface diffusion assisted phase separations is, however, lacking. Here the influence of low energy (50-130 eV) assisting Ar+ ion irradiation on the morphology of C-Ni thin films will be reported. Ion-beam assisted deposition (IBAD) promotes the columnar growth of carbon encapsulated metallic nano-columns at low deposition temperatures for Ar+ ion energy ranges of 50-100 eV. Moreover, the momentum transfer results in a tilting of the columns relative to the film surface. The potential to grow complex matrix encapsulated metallic structures such as chevrons is demonstrated. Furthermore, a window of deposition conditions will be reported where the ion assistance leads to the formation of regular 3D nanopatterns with well-defined periodicity. The influence of such anisotropic film morphology on the optical properties is highlighted.
Acknowledgements: Funding by the European Union, ECEMP-Project D1, "Nanoskalige Funktionsschichten auf Kohlenstoffbasis", Projektnummer 13857 / 2379, is gratefully acknowledged.