Variation of threshold field in field induced fabrication of Au nanodots on ultrathin in situ grown silicon oxide

Abstract

We report on the variation of threshold field with oxide thickness for field evaporation of Au nanodots onto ultrathin oxide layers on Si(1 0 0). Au dots of 1-10 nm diameter were fabricated on an in situ oxidized Si(1 0 0) substrate by the application of a voltage pulse between an Au coated STM tip and the sample. Under feedback-controlled tunneling conditions (V-s = 2 V, I-t = 3 nA), the voltage required for field deposition increased roughly linearly from 5.8 to 11 V as average oxide thickness increased from 0 to 8 Angstrom. This corresponds to a change in the threshold field of about 0.3 V/Angstrom, which is roughly consistent with a calculation based on shielding of the image charge by the intervening oxide layer. (C) 2000 Elsevier Science B.V. All rights reserved.