Microscopy and Microanalysis

Software, Techniques and Equipment Development

The Influence of the Sample Thickness on the Lateral and Axial Resolution of Aberration-Corrected Scanning Transmission Electron Microscopy

Ranjan Ramachandraa1 p1, Hendrix Demersa2 p2 and Niels de Jongea1a3 c1

a1 Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, TN 37232-0615, USA

a2 University of Sherbrooke, Electrical and Computer Engineering Department, Sherbrooke, Quebec J1K 2R1, Canada

a3 INM—Leibniz Institute for New Materials, 66123 Saarbrücken, Germany

Abstract

The lateral and axial resolution of three-dimensional (3D) focal series aberration-corrected scanning transmission electron microscopy was studied for samples of different thicknesses. The samples consisted of gold nanoparticles placed on the top and at the bottom of silicon nitride membranes of thickness between 50 and 500 nm. Atomic resolution was obtained for nanoparticles on top of 50-, 100-, and 200-nm-thick membranes with respect to the electron beam traveling downward. Atomic resolution was also achieved for nanoparticles placed below 50-, 100-, and 200-nm-thick membranes but with a lower contrast at the larger thicknesses. Beam broadening led to a reduced resolution for a 500-nm-thick membrane. The influence of the beam broadening on the axial resolution was also studied using Monte Carlo simulations with a 3D sample geometry.

(Received June 20 2012)

(Accepted September 04 2012)

Key words

  • scanning transmission electron microscopy;
  • point spread function (PSF);
  • 3D;
  • beam broadening;
  • axial resolution;
  • nanoparticles

Correspondence:

c1 Corresponding author. E-mail: niels.dejonge@inm-gmbh.de

p1 Current affiliation: Center for Research in Biological Systems, University of California at San Diego, La Jolla, CA, USA

p2 Current affiliation: Department of Materials Engineering, McGill University, Montréal, Québec, Canada