Fabrication of zinc nanotip arrays by ion beam sputtering

Zinc nanotip arrays were fabricated on polycrystalline zinc foils using capillaritron ion beam sputtering. The geometry and structure of the nanotip are found to be dependent on the ion species, beam energy, and exposure fluence. After 12 keV argon ion beam sputtering, zinc nanotips with end radii less than 5 nm and aspect ratios larger than 20 were obtained. Cone-shaped nanostructures with an aspect ratio of 3 and tip radius of 25 nm were found after oxygen ion beam sputtering. Energy dispersive x-ray spectroscopy and scanning electron microscopy analysis indicate that the high aspect ratio nanotip formation mechanism after argon ion beam sputtering is due to differential erosion and anisotropic hardness of zinc nanocrystal, while the formation mechanism of cone-shaped nanostructures after oxygen ion beam sputtering is due mainly to the formation of ZnO on the apex, acting as an etch stop. The field emission properties of zinc nanotips are presented. (c) 2007 American Vacuum Society.