Ionic/electronic mixed conductor tip of a scanning tunneling microscope as a metal atom source for nanostructuring

Abstract

Silver sulfide $({\mathrm{Ag}}_2\mathrm{S})$ which has Ag-ionic/electronic mixed conductivity is used for fabricating a tip used for a scanning tunneling microscope. The mixed conductor tip is capable of nanostructuring by depositing Ag atoms continuously on a sample as well as imaging the surface structure. To obtain the surface image, a nanoscale Ag protrusion is formed at an apex of the tip using a local solid electrochemical reaction, working as “a mini-tip.” We fabricate a nanoscale line structure on the sample by scanning the ${\mathrm{Ag}}_2\mathrm{S}$ tip with the protrusion under appropriate bias voltages and tunneling currents. The structuring is thought to be made up of two layers of Ag atoms deposited from the protrusion.