Controlling electron transfer processes on insulating surfaces with the non-contact atomicforce microscope

Abstract

We present the results of theoretical modelling that predicts how a process of transfer ofsingle electrons between two defects on an insulating surface can be induced using ascanning force microscope tip. A model but realistic system is employed which consists of aneutral oxygen vacancy and a noble metal (Pt or Pd) adatom on the MgO(001) surface. Weshow that the ionization potential of the vacancy and the electron affinity of the metaladatom can be significantly modified by the electric field produced by an ionic tip apex atclose approach to the surface. The relative energies of the two states are also afunction of the separation of the two defects. Therefore the transfer of an electronfrom the vacancy to the metal adatom can be induced either by the field effectof the tip or by manipulating the position of the metal adatom on the surface.