Paper EW-TuA2
Latest Developments and Application of the Qtac100 for High Sensitivity LEIS

Tuesday, October 21, 2008, 3:40 pm, Room Exhibit Hall

The new high sensitivity and high resolution Low Energy Ion Scattering (LEIS) instrument, the Qtac³, delivers quantitative top atomic layer characterization. It is able to quantitatively analyze the outermost atomic layer of a solid and gain in-depth information in a non-destructive way. The surface is bombarded with low energy (up to 8 keV) noble gas ions that scatter from individual surface atoms. The energy of the ions after scattering is characteristic of the mass of the surface atom. If the scattering event occurs below the surface, an additional depth dependent energy loss can be measured, providing information about the composition of the sample up to 10 nm deep (“static depth profiling”). With its unique energy analyzer, the scattered ions are detected with high sensitivity, while simultaneous high mass resolution allows unambiguous elemental identification. With a pulsed ion beam and time-of-flight filtering, the background of sputtered ions can be resolved from the scattered ions, improving the detection limits for light elements and for trace element detection. Together, this allows an application of the Qtac to many technologically relevant fields. We will present the latest developments of the Qtac100, and show the benefit of the instrument to a variety of applications from traditional surface science to industrial uses. Among these, semiconductor materials (e.g. thin films, layer growth) and heterogeneous catalysts (e.g. Au/Pt nano-clusters, determination of poisoning sites) are the most prominent ones, but other fields that require quantitative top atomic layer characterization will also be addressed.