a1 Carl Zeiss SMT Inc., One Corporation Way, Peabody, MA 01960, USA
a2 Center for NanoPhase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6496, USA
a3 Centre for Microscopy, Characterization and Analysis (M010), University of Western Australia, Crawley, WA 6009, Australia
a4 Electron Microscopy Facility, University of Tennessee, Knoxville, TN 37996-0840, USA
The scanning helium ion microscope has been used in transmission mode to investigate both the feasibility of this approach and the utility of the signal content and the image information available. Operating at 40 keV the penetration of the ion beam, and the imaging resolution achieved, in MgO crystals was found to be in good agreement with values predicted by Monte Carlo modeling. The bright-field and annular dark-field signals displayed the anticipated contrasts associated with beam absorption and scattering. In addition, the diffraction of the He ion beam within the sample gave rise to crystallographic contrast effects in the form of thickness fringes and dislocation images. Scanning transmission He ion microscopy thus achieves useful sample penetration and provides nanometer scale resolution, high contrast images of crystalline materials and crystal defects even at modest beam energies.
(Received December 28 2009)
(Accepted April 24 2010)