Aberration-corrected Electron Holograms Carry Information about Atomic Bonding
16 March 2017
A team of researchers from the Peter Grünberg Institute and the Ernst Ruska-Centre (ER-C) in Jülich, the RWTH Aachen University and the University of Liège has succeeded in paving the way towards the fully quantitative imaging of the electronic properties of crystalline imperfections, such as point defects, on the atomic scale using electron holography. This information is important for the atomic scale engineering of materials such as catalysts and single dopants in devices for quantum information.
In electron holography, a high-energy electron beam can be used to image electrostatic potentials in materials with atomic spatial resolution. “Recent technical improvements in electron microscopy, such as spherical and chromatic aberration correction, have allowed us to make the next step towards quantitative electron microscopy with sub-Ångström resolution using comparatively low electron energies”, explained Dr. Juri Barthel, a scientist in the ER-C-2 institute. This capability now enables the detailed imaging of radiation-sensitive tungsten diselenide with atomic resolution.
The researchers have shown that computational models based on density functional theory are required to provide a match to experiments, which they performed on tungsten diselenide. This two-dimensional material is of interest for optoelectronic applications. The calculations include an accurate treatment of atomic bonding effects, which are associated with a small redistribution in charge but have a strong influence on the probe electrons. “Excellent agreement between our experimental images and simulations strongly surpasses previous comparisons with theoretical methods used in this field”, added Prof. Rafal Dunin-Borkowski, Director at the ER-C.
Further information:
Original Publication:
Quantitative Agreement between Electron-Optical Phase Images of WSe2 and Simulations Based on Electrostatic Potentials that Include Bonding Effects;
S. Borghardt, F. Winkler, Z. Zanolli, M. J. Verstraete, J. Barthel, A. H. Tavabi, R. E. Dunin-Borkowski, and B. E. Kardynal;
Phys. Rev. Lett. 118, 086101 – Published 22 February 2017