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Title:Surface diffusion processes critical to metallic film nucleation and growth: An atomic view
Author(s):Liu, Chun-Li
Doctoral Committee Chair(s):Adams, James B.
Department / Program:Engineering, Chemical
Engineering, Metallurgy
Engineering, Materials Science
Discipline:Engineering, Chemical
Engineering, Metallurgy
Engineering, Materials Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Chemical
Engineering, Metallurgy
Engineering, Materials Science
Abstract:Extensive computer simulations have been performed to study diffusion processes critical to nucleation and growth of metallic thin films. Diffusion behavior of (1) single adatoms on a flat surface, (2) single adatoms near and at steps on a vicinal surface, and (3) small adatom cluster migration on terraces and (4) single vacancies on a flat surface has been investigated. Many important results have been found. For instance, (i) For adatom diffusion near steps on Ni(111) there exists a "forbidden" region near steps. The adatoms have to overcome a slightly higher energy barrier to get into the "forbidden" region. This is consistent with the latest FIM experiments for Ir adatom diffusion near Ir clusters on Ir(111). (ii) Exchange diffusion at descending steps of type B on Ni(111) was found to be energetically favored and is the dominant mechanism for incorporation of adatoms over descending steps into the step ledges. This is consistent with earlier FIM experiments for W adatom diffusion at Ir cluster steps on Ir(111). (iii) Diffusion of adatoms along the step ledges can be either enhanced, as on Ni(100), or hindered, as on Ni(111). (iv) For the first time an exchange mechanism was found to be favored at descending steps on Ni(110) and (100). (v) The energy barriers for vacancy diffusion on five fcc surfaces were found to be higher than those for single adatom diffusion. (vi) Small clusters migrate in different fashions on different surfaces: on Ni(100) they move through a series of individual jumps of single atoms in the clusters; on Ni(111), for the first time they were found to migrate by concerted jumps of all the atoms in the clusters. The trend in the energy barriers on both surfaces was found to be consistent with available FIM experimental data.
Issue Date:1993
Rights Information:Copyright 1993 Liu, Chun-Li
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9314906
OCLC Identifier:(UMI)AAI9314906

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