Instrumentation and analytical methods of an x-ray photoelectron spectroscopy–scanning tunneling microscopy surface analysis system for studying nanostructured materials

The design and performance of an x-ray photoelectron spectroscopy (XPS)–scanning tunneling microscopy (STM) surface analysis system for studying nanostructured materials are described. The analysis system features electron spectroscopy methods (XPS and Auger electron spectroscopy) in addition to a variable temperature STM. With the analytical methods of the system, surface chemical analysis as well as surface morphology down to atomic resolution can be obtained. The system also provides facilities for sample cleaning, annealing, gas dosing, depth profiling, and surface modifications by sputtering and evaporation. Controlled gas exposures from ultrahigh vacuum to atmospheric pressures in the adjustable temperature range of 120–1100K can be carried out in different chambers. A fast entry air lock allows the transfer of samples and STM tips into the system without air exposures. The surface analysis system uses a common sample holder in all five chambers which are independently pumped and separated from each other by gate valves. Thus, it is possible to make all sample preparations and experiments in situ under well-defined conditions as illustrated by the formation and characterization of strained, self-assembled nano-oxides on Cu(100).