NANOFABRICATION OF LAYERED MATERIALS WITH THE SCANNING TUNNELING MICROSCOPE

This paper reports selective etching and deposition (nanofabrication) on the surface of layered materials under the scanning tunneling microscope (STM) tip. Materials such as highly oriented pyrolytic graphite (HOPG), MoS2, NbSe2 and Bi2Sr2CaCu2Ox are investigated in air and in ultra-high vacuum. The etching is performed by applying positive substrate bias voltages. Negative bias voltages cause atom clusters to be deposited on the surface from the tip. Threshold bias voltages (V-t) for etching and deposition are defined as the voltages above which nanofabrication is possible with the STM. Comparison of the V-t values with the binding energies of materials leads us to attribute the etching mechanism in UHV to the sublimation of surface atoms induced by the tunneling electrons. On the other hand, oxidation by adsorbed water lowers the energy for etching in air. Furthermore, using the relationship between the V-t and the binding energy of the materials, the possibility of identification of atoms with the STM is discussed.