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O: Fachverband Oberflächenphysik

O 73: Scanning Probe Methods II

O 73.10: Vortrag

Donnerstag, 3. April 2014, 12:45–13:00, WIL A317

Secondary Electron Analysis with Topografiner Technology — •Lorenzo G. De Pietro, Danilo A. Zanin, Hugo Cabrera, Mehmet Erbudak, Andreas Fognini, Thomas U. Michlmayr, Yves M. Acremann, Danilo Pescia, and Urs Ramsperger — ETH Zurich, Switzerland

In Near Field-Emission Scanning Electron Microscopy (NFESEM), based on the topografiner technology, cold field emitted electrons from a sharp polycrystalline W-tip are the source of a primary electron beam. The applied voltage for field emission (between the tip and the sample) accelerates these electrons up to some tens of eV. After having interacted with the sample, secondary and backscattered electrons are detected, while an STM controller is used to scan the tip at a constant distance (10 to 20 nm) from the sample surface. This technique has been used to take topography images of various metals and semiconductors achieving subnanometer lateral resolution. In case of a W(110) surface partially covered by Fe a chemical contrast was observed. After having implemented energy analysis to this technique, we present a series of images generated by collecting only electrons with selected energies, i.e. true secondary electrons. This represents an important step in view of adding a spin polarization analysis and use the NFESEM as an instrument to investigate magnetic surfaces at a nanometer scale.