Characterization and modeling of nanotips fabricated in the field ion microscope

Abstract

Nanotips are considered significant elements in some of nanotechnology instruments. They are used in scanning probe microscopes and electron microscopes to characterize materials at the nano and atomic scales. Therefore, the size and profile of the nanotip determines the performance of these microscopes. The advancement of nanotip fabrication techniques has enabled the fabrication of ultra-sharp tips and even single-atom tips. However, the characterization of nanotips with an apex of a few nanometers is still premature, while the conventional characterization methods of the tip size, such as the ring counting method, have shown some limitation at this nano scale. In this paper, we review the various nanotip fabrication methods with a focus on the most recent one, which is called the local electron bombardment method. We demonstrate an approach for estimating the nanotip radius with good approximation using ball crystal models. We also model the overall nanotip profile using finite element simulation tools based on the hyperboloidal geometry. The modeling and radius estimation approach is applied on tips fabricated by the local electron bombardment method, which will be explained in detail as well.