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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 Degree: Ph.D. Genre: Dissertation 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 Type: Text Description: 202 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1992. URI: http://hdl.handle.net/2142/72141 Other Identifier(s): (UMI)AAI9305686 Date Available in IDEALS: 2014-12-17 Date Deposited: 1992
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