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

Silver sulfide (Ag2S) 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 Ag2S 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.