| AVS 61st International Symposium & Exhibition | |
| Helium Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI+2D+AS+BI+MC-ThM |
| Session: | Fundamental Aspects and Imaging with the Ion Microscope |
| Presenter: | Jason Pitters, National Institute for Nanotechnology, Canada |
| Authors: | J.L. Pitters, National Institute for Nanotechnology, Canada R. Urban, National Institute for Nanotechnology, Canada R. Wolkow, University of Alberta and The National Institute for Nanotechnology, Canada |
| Correspondent: | Click to Email |
Single atom tips (SATs) prepared by the spatially controlled field assisted etching method are proving to have utility as ion sources, electron sources and in scan probe applications.
As Gas Field Ion Sources (GFISs), there is potential for operation in scanning ion microscopes (SIMs) and our efforts to prepare and characterize SAT ion emission will be discussed. It will be shown that etching to a single atom tip occurs through a symmetric structure and leads to a predictable last atom. SATs can be prepared reproducibly with emission along a fixed direction for all tip rebuilds. It will also be shown that the emission properties of the SAT can be altered by shaping of the tip shank during the etching procedure. In this manner, the operating voltage can be controlled and a lensing effect of the tip base is demonstrated. During formation, the tip shape can be evaluated by using both helium and neon imaging gases. The stability of helium and neon ion beams generated by SATs will also be demonstrated and compared to other tip orientations. The remarkable robustness of these tips to atmosphere exposure will also be shown and the ability to prepare SATs from material other than tungsten will be demonstrated.
SATs also have utility in electron emission. By shaping the tip appropriately, electron emission characteristics can also be tailored and the coherence properties of an SAT will be presented as deduced from holographic measurements in a low-energy electron point source microscope. Initial utility in scan probe experiments including atomic force microscopy and scanning tunneling microscopy will also be discussed.