ELECTROCHEMICAL MODIFICATIONS AT THE NANOMETER-SCALE ON SI(100) SURFACES WITH SCANNING-TUNNELING-MICROSCOPY

Scanning Tunnelling Microscopy is used as a tool to produce nanometer scale modifications on hydrogen passivated silicon (100) surfaces unde r positive and negative sample vs, tip voltage. Experiments have been performed in air and 'in situ' in an HF solution. In air, it is found that under both polarities the surface under the tip becomes oxidized and that the oxidation is possible although no tunnelling current flow s between tip and sample. Taking into account the band bending in the semiconductor, it is shown that the oxidation is a field induced proce ss. Experiments 'in situ' demonstrate that two different mechanisms ex ist: oxidation at anodic polarization and direct silicon etching at ca thodic polarization. (C) 1998 Elsevier Science S.A.