FIELD EVAPORATION OF METAL ATOMS ONTO INSULATOR CONDUCTING SUBSTRATE USING ATOMIC-FORCE MICROSCOPE

The feasibility of field-evaporating metal atoms onto an insulator/conducting substrate has been investigated. Theoretical and experimental studies clarify that field evaporation is possible in an atomic force microscope (AFM) metal probe/vacuum/thin insulator/conductor configuration. Theoretically, field evaporation is easily achieved on thin SiO2 insulators of less than 100 Angstrom, though image potential and electric field weaken in the presence of an insulating layer. Experiments confirm that ultrasmall gold dots can be formed on a natural SiO2/Si substrate with a threshold voltage of around 10 V. Small dots of 15 nm diameter can be obtained.