title: The New Methodology and Chemical Contrast Observation by Use of the Energy-Selective Back-Scattered Electron Detector.
abstract: We report on a robust method for chemical element-sensitive imaging by scanning electron microscopy (SEM). The commercial Auriga FE-SEM microscope (Carl Zeiss, Oberkochen, Germany), equipped with an energy-selective grid detector (EsB) as a part of the experimental setup, was applied for generation of chemical contrast at low accelerating voltages, which is gentle for sensitive samples. The EsB-grid detector, conceptually adapted by us as an energy retarding field analyzer (RFA), was used to detect the two-dimensional (2D) energy spectrum for the first time. The electron energy spectrum measured by sweeping the retarding grid potential revealed thresholds corresponding to electronic transitions in the specimen, followed by 2D-derivation treatment applied just at the observed thresholds. This allowed chemical mapping by SEM. In this report the 273 eV Auger transition in carbon deposited onto the Si(100) sample was chosen as a source for chemical contrast in the SEM image. In addition to Auger electrons, we expect analogous energy-selective contrast enhancement for inelastically scattered electrons, for example, in plasmonic contrast and elastically scattered electrons, for example in phase contrast, our method, proved for carbon, is expected to apply to a broader list of elements as a general capability of chemical mapping, at several-fold better lateral resolution when compared with energy dispersive spectroscopy (EDS).
authors.affiliation: 1USI,Unit of Nanostructural Bio-Interactions,Institute of Immunology and Experimental Therapy,Polish Academy of Sciences,Weigla 12 Street,53-114 Wroclaw,Poland.
authors.forename: Marek
authors.identifier: 0000-0002-2771-1692
authors.initials: M
authors.lastname: Drab
authors.affiliation: 2Laboratory of Isotope Geology and Geoecology,Department of Applied Geology,Geochemistry and Environmental Management,Institute of Geological Sciences,University of Wroclaw,Cybulskiego 30,50-205 Wrocław,Poland.
authors.forename: Janusz
authors.initials: J
authors.lastname: Krajniak
authors.affiliation: 3Faculty of Microsystem Electronics and Photonics,Division of Microelectronics and Nanotechnology,Wroclaw University of Science and Technology,Dluga Street 65,53-633 Wroclaw,Poland.
authors.forename: Krzysztof P
authors.initials: KP
authors.lastname: Grzelakowski
keywords: 2D derivation; Auger transitions; chemically selective imaging; elemental mapping; low-voltage FE-SEM