Experimental detection limits in scanning auger microscopy at high lateral resolution

Using a scanning Auger microscope at 100 keV primary beam energy it has been possible to analyse a dispersed catalyst particle by particle. The elemental analysis of a 8 nm particle has been obtained for which the number of Pd atoms being detected is estimated to be less than 4000, leading to a detectable mass of 7 × 10−19 g. A silicon sub-monolayer buried in a GaAs matrix has also been detected, operating at oblique incidence with a 20 nm beam size (minimum detectable concentration < 2 × 10−3). These preliminary experiments illustrate the potential of performing Auger spectroscopy at unconventional primary beam energies (with a field emission gun) when high lateral resolution is required.