Probing electron transport and structural properties of nanostructures on Si with a quadra-probe scanning tunneling microscope

The electron transport and structural properties of nanostructured materials have been examined with a newly developed low temperature quadra-probe scanning tunneling microscope (STM). The quadra-probe STM system, as a "nano" version of four-probe station, provides an integrated research platform with a low temperature 4-probe STM, a molecular-beam epitaxy growth chamber, a high resolution scanning electron microscope, and a scanning Auger microscope. The four STM probes can be driven independently with sub-nanometer precision, enabling conventional STM imaging and four-point electrical transport study of surface electronic systems and nanostructured materials at temperatures down to 10 K. Self-assembled nanostructures grown on Si by doping with metal atoms (Au, Gd, Ag) have been fabricated and characterized in situ.