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This is an abstract for a talk to be given at the Fifth Foresight Conference on Molecular Nanotechnology.
I will discuss the use of the STM and AFM to induce controlled local modifications of the structure and composition of surfaces and the fabrication of nanostructures. First, I will discuss modifications based on mechanical tip-sample interactions. As an example, I will use the manipulation of carbon nanotubes with the AFM. I will then concentrate on local chemical bond breaking using tip-induced sample excitations. In particular, I will focus on the process of Si-H bond cleaving and H desorption from silicon surfaces. Experiments and theoretical results will be used to show that two distinct mechanisms involving, respectively, electronic and multiple-vibrational excitation of the Si-H unit, lead to desorption. The characteristics of the two mechanisms, i.e. energy thresholds, cross-sections, current, and temperature dependencies and isotope effects will be presented and analyzed. As an example of bond cleaving by tip-emitted electrons, I will discuss the selective O-O and Si-O bond breaking via dissociative electron attachment processes. Finally, electric field-induced modification will be demonstrated using the AFM tip-induced oxidation of Si and metals. I will discuss the kinetics and mechanism of the process and determine how such factors as the strength of the electric field, ambient humidity, and thickness of the oxide affect its rate and spatial resolution. The electrochemical character of the process at low bias will be demonstrated, and a second component of the reaction involving current-driven oxidation will be identified. Using this AFM-induced oxidation process, we have fabricated model nanostructure and devices whose electrical properties I will discuss.
Phaedon Avouris, IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598, ph: 914-945-2722, fax: 914-945-4531, email: email@example.com
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