Dresden 2006 – scientific programme
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MM: Metall- und Materialphysik
MM 30: Symposium Nano Wires (SYNW)
MM 30.5: Talk
Thursday, March 30, 2006, 12:00–12:15, IFW D
Electric Field Induced Low Temperature Oxidation of Tungsten Nanowires — •C. Nowak1, G. Schmitz2, and R. Kirchheim1 — 1Institut für Materialphysik, Universität Göttingen, D-37077 Göttingen — 2Institut für Materialphysik, Universität Münster, D-48149 Münster
A study on room temperature oxidation of tungsten nanowires is presented, utilizing the high electric field arising at the tip of a nanowire if a moderate voltage is applied to influence the oxidation process.
Experiments were performed at room temperature under ambient atmosphere, TEM was applied to investigate the nanowires afterwards. Above a critical field strength, oxide layer formation occurs and is observed to virtually terminate at a field dependent state, determined by a critical field strength of 1.14(2)×109 V/m at the oxide-gas interface. This allows the controlled formation of oxide layers up to several 10 nm thick in the high field region at the tip of the nanowires. Diffraction pattern analysis reveals that the oxide is vitreous or nanocrystalline with a grain size of several nanometers. Additionally considering the stoichiometry it is concluded that mainly WO3 is formed. The observed electric field induced modification of the natural oxidation process is discussed within the scope of the Cabrera and Mott theory of low temperature oxidation, particularly focusing on the aspect of charge compensation at the oxide-gas interface.