Scanning tunnelling microscope-induced oxidation of hydrogen passivated silicon surfaces


Kramer, N. and Berg, M.R. van den and Schönenberger, C. (1996) Scanning tunnelling microscope-induced oxidation of hydrogen passivated silicon surfaces. Thin Solid Films, 281-28 (1-2). pp. 637-639. ISSN 0040-6090

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Abstract:We have investigated the mechanism of scanning tunnelling microscope (STM)-induced oxidation of a hydrogen passivated silicon surface in air. The influence of the relative air humidity, the Si doping concentration and the type and applied tip-sample voltage on the oxidation process was studied. The relative air humidity is crucial, if the relative air humidity drops below 10% no oxidation is observed. The width of the oxide lines increases with increasing tip-sample voltage. The voltage required to produce oxide lines on p-type Si is −1.1 V and does not depend on the doping concentration. For n-type Si, the threshold voltage for oxidation varies from −2.4 V for heavily doped to −3.5 V for lightly doped. A simple model is developed in which the electrical field between the tip (estimated as a sphere) and the substrate was calculated. We assume that a critical field is required to induce the oxidation. With this model, a good fit can be obtained with the experimentally found line-width dependence of the voltage. In addition, the effect of the doping type and concentration can be understood if depletion, in the case of n-type silicon, is included.
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Copyright:© 1996 Elsevier Science
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Metis ID: 128940