title: Channeling in helium ion microscopy: Mapping of crystal orientation.
abstract: BACKGROUND
  The unique surface sensitivity and the high resolution that can be achieved with helium ion microscopy make it a competitive technique for modern materials characterization. As in other techniques that make use of a charged particle beam, channeling through the crystal structure of the bulk of the material can occur.
  
  
  RESULTS
  Here, we demonstrate how this bulk phenomenon affects secondary electron images that predominantly contain surface information. In addition, we will show how it can be used to obtain crystallographic information. We will discuss the origin of channeling contrast in secondary electron images, illustrate this with experiments, and develop a simple geometric model to predict channeling maxima.
  
  
  CONCLUSIONS
  Channeling plays an important role in helium ion microscopy and has to be taken into account when trying to achieve maximum image quality in backscattered helium images as well as secondary electron images. Secondary electron images can be used to extract crystallographic information from bulk samples as well as from thin surface layers, in a straightforward manner.
authors.affiliation: Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500AE Enschede, The Netherlands.
authors.forename: Vasilisa
authors.initials: V
authors.lastname: Veligura
authors.forename: Gregor
authors.initials: G
authors.lastname: Hlawacek
authors.forename: Raoul
authors.initials: R
authors.lastname: van Gastel
authors.forename: Harold J W
authors.initials: HJ
authors.lastname: Zandvliet
authors.forename: Bene
authors.initials: B
authors.lastname: Poelsema