The kinetics and mechanism of scanned probe oxidation of Si

We report measurements of the kinetics of scanned probe oxidation under con ditions of high humidity and pulsed bias. For a hydrophobic Si surface the oxidation rate for short pulse times (similar to 10 ms) is controlled by th e density of H2O molecules in the ambient humidity surrounding the tip-samp le interface. At longer pulse times (similar to 0.1 s) liquid H2O bridges t his interface and the maximum oxidation rate increases by a factor of simil ar to 10(4) because of the increased density of H2O molecules. We propose t hat the rate-limiting step of the oxidation process is the production of O anions from the ambient humidity. (C) 2000 American Institute of Physics. [ S0003-6951(00)04013-4].