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Title:Surface Diffusion of Antimony on Germanium(111) Investigated by Second Harmonic Microscopy
Author(s):Schultz, Kurt Alan
Doctoral Committee Chair(s):Seebauer, Edmund G.
Department / Program:Chemical Engineering
Discipline:Chemical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Physical
Physics, Condensed Matter
Physics, Optics
Abstract:Surface diffusion of Sb on Ge(111) has been measured with the newly-developed technique of second harmonic microscopy. In this method, concentration profiles at submonolayer coverage are imaged directly by second harmonic generation with 5 $\mu$m spatial resolution. A Boltzmann-Matano analysis of the concentration profiles yields the coverage dependence of the diffusivity D without parameterization. Experiments were performed at roughly 70% of the bulk melting temperature T$\sb{\rm m}.$ In the coverage range of $0<\theta<0.6,$ the activation energy E$\sb{\rm diff}$ remains constant at 47.5 $\pm$ 1.5 kcal/mol. The corresponding pre-exponential factor decreases from 8.7 $\times$ 10$\sp{3\pm0.4}$ to 1.6 $\times$ 10$\sp{2\pm0.4}$ cm$\sp2$/sec. The results are explained in terms of a new vacancy model for surface diffusion at high-temperatures. The model accounts semiquantitatively for the large values of E$\sb{\rm diff}$ and D$\sb{\rm o},$ and suggest that these quantities may be manipulated by bulk doping levels and photon illumination of the surface.
Issue Date:1992
Description:202 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1992.
Other Identifier(s):(UMI)AAI9305686
Date Available in IDEALS:2014-12-17
Date Deposited:1992

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