STM tip-induced nanoscale etching on the H-terminated n-Si(111) surfaces under the potential control

The H-terminated n-Si(111) surface is found to be etched locally under the STM tip in the dilute HF solution by applying a given positive potential to the tip while keeping the silicon electrode potential near its flat-band p otential, at which the oxidative etching of silicon is not expected to occu r in the absence of light. The induced etching rate is shown to depend on t he tunneling current. The mechanism of the etching process is proposed on t he basis that the tunneling of electrons occurs directly from the valence b and of the silicon electrode into the empty stares at the tip, leading to a hole injection in the silicon surface, followed by an electrochemical oxid ation on the local surface underneath the tip. (C) 2000 Elsevier Science B. V. All rights reserved.