Development of electron source for Auger electron spectroscopy in scanning probe microscope systems

We have developed a scanning tunneling microscope (STM) combined with an Auger electron energy analyzer for both topography observation and element analysis on surfaces. A special STM tip was designed for a field-emission source that induces the Auger process. We found that a simple STM tip is not effective, since the trajectories of Auger electrons ejected from the surface are bent considerably by the high electric field between the surface and the tip. Instead, the shield electrode around the tip reduces the bending, and carbon Auger electrons (KLL) ejected from the highly oriented pyrolytic graphite were detected. In future, such an Auger-STM will enable both types of observation conveniently on the same region by changing modes between topography and Auger measurements.