Field evaporation in the configuration of a scanning tunneling microscope

The paper introduced an effective binding energy Λ′eff and emphasized the role it plays in the field evaporation in the configuration of a scanning tunneling microscope (STM). With this Λ′eff an important modification has been made to Tsongʹs CE model formula for STM [Tien T. Tsong, Phys. Rev. B 44 (1991) 13 703]. As a consequence, for tip–sample distance 5<d<13 Å, the high evaporation fields from Tsongʹs original formula were found greatly reduced. When d=7.23 Å, the recalculated evaporation field for Au−1 is 0.6 V/Å, which is in good agreement with Changʹs experiment [Phys. Rev. Lett. 72 (1994) 574]. Further the evaporation field was found highly localized. For d=7.52 Å, the evaporation field of Au−1 on top of a Au(1 1 1) surface atom was found several times lower than that at a hollow site. In the calculation we have proposed a universal binding function. In addition selected experimental results on nanostructure formation by positive or negative voltage pulses with Au, Ni, Cu, Pt(Ir) and W tips on Au(1 1 1) substrate with a STM working in atmosphere were presented. The processes were found to bear important feature of field evaporation.