In Situ Microfabrication and Measurements of Bi₂Se₃ Ultrathin Films in a Multichamber System with a Focused Ion Beam, Molecular Beam Epitaxy, and Four-Tip Scanning Tunneling Microscope

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Ultrathin films of Bi₂Se₃ grown on Si(111) substrate were etched into submicron-width wires by using a focused ion beam (FIB), and their electrical resistance was measured using the four-probe method with a four-tip scanning tunneling microscope. All of the procedures were performed in situ in ultrahigh vacuum without exposing the sample to air. One-dimensional conduction of the films was confirmed from the dependence of the resistance on the length of wire under measurement, meaning that successful lossless current path control laterally as well as vertically can be obtained with FIB etching. Protecting the sample surface from unintentional gallium ion beam irradiation in the FIB process was also found to be important for maintaining the intrinsic electrical properties of the Bi₂Se₃ films. [DOI: 10.1380/ejssnt.2014.423]