STM tip induced local etching and deposition on Cu surfaces

At cathodic potential of bulk copper deposition in dilute Cu2+ solution, ti p was found to be able to induce local dissolution of copper by applying a rather positive tip potential, although meanwhile the copper was still depo sited on the surface far from the tip area, The more positive the tip poten tial or the electrode potential is, the faster induced dissolution rate is, At a rather negative tip potential, deposition of Cu was enhanced by the t ip while in the case Cu was dissolved locally with a more positive tip pote ntial. A mechanism based on overlap of double layers between tip and substr ate was proposed.