| AVS 54th International Symposium | |
| Applied Surface Science | Wednesday Sessions |
| Session AS-WeM |
| Session: | Chemical Imaging at High Spatial Resolution and Nanoscale Materials |
| Presenter: | N. Barrett, CEA-Saclay, FR |
| Authors: | N. Barrett, CEA-Saclay, FR O. Renault, CEA LETI Minatec, FR L.-F. Zagonel, CEA Saclay, FR A. Bailly, CEA LETI Minatec, FR J. Charlier, CEA Saclay, FR J. Leroy, CEA Saclay, FR J.C. Cezar, ESRF, FR N. Brookes, ESRF, FR M. Senoner, Fed. Inst. Mtls Testing, Germany J. Maul, Univ. of Mainz, Germany T. Berg, Univ. of Mainz, Germany F. Schertz, Univ. of Mainz, Germany G. Schönhense, Univ. of Mainz, Germany |
| Correspondent: | Click to Email |
The combination of high brightness photon source and aberration corrected energy filtering has allowed new progress in the field of electron emission microscopy for nanoscience and nanotechnology. The first commercially available NanoESCA instrument (OMICRON GmbH) has been recently commissioned and tested at the CEA Nanocharacterization centre (Minatec) in Grenoble and on beamline ID08 at the ESRF. We first present the principles of spectromicroscopy, and in particular the use of an electrostatic PEEM column together with an energy aberration corrected double hemispherical analyzer. The objective immersion lens and the high extraction voltage considerably improve lateral resolutions. The use of a contrast aperture reduces the chromatic aberrations in the PEEM column. The accurate focus tracking of the instrument allows imaging at the secondary electron threshold and across specific core levels at chosen kinetic energies. The resulting lateral resolution better than 150 nm and energy resolution give an imaging capability with full chemical state sensitivity. The principles will be illustrated by several examples. The core level intensity contrast is demonstrated with a multilayer certified standard sample of GaAs/GaxAl1-xAs variable multilayer. The energy resolved chemical mapping will be illustrated via the preferential molecular grafting on a heterogeneous Au-Si substrate. Finally, the depth resolution thanks to the variable photoelectron escape depth is employed to do non-destructive position detection of pre-solar grains coming from a meteorite, prior to nano-SIMS analysis. The perspectives include reaching the ultimate resolution limits using an optimized synchrotron beamline, the development of valence band imaging and the study of single nanodevices.