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Growth kinetics of CaF[sub 2]/Si(111) heteroepitaxy: An x-ray photoelectron diffraction study

Journal Article · · Physical Review, B: Condensed Matter; (United States)
;  [1]; ; ;  [2]
  1. Department of Physics and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
  2. Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)
Kinetic variations of the initial stages of CaF[sub 2] growth on Si(111) by molecular-beam epitaxy are studied with the [ital in] [ital situ] combination of x-ray photoelectron spectroscopy and diffraction. After the formation of a chemically reacted interface layer, the morphology of the subsequent bulk layers is found to be dependent on the substrate temperature and incident flux rate, as well as the initial interface structure. For substrate temperatures above [similar to]600 [degree]C, subsequent layers do not easily wet the interface layer, and a transition is observed from a three-dimensional island formation at low flux to a laminar growth following the coalescence of bilayer islands at higher flux. At lower substrate temperatures ([similar to]450 [degree]C), a different stoichiometry and structure of the interface layer leads to laminar growth at all fluxes, but with a different bulk nucleation behavior. Crystalline heteroepitaxy is not observed when growth initiates at room temperature, but homoepitaxy does proceed at room temperature if the first few layers are deposited at a high temperature. The different growth regimes are discussed in terms of a kinetic model separating step and terrace nucleation where, contrary to homoepitaxy, step nucleation leads to islanded growth.
DOE Contract Number:
AC03-76SF00098
OSTI ID:
6604411
Journal Information:
Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 51:8; ISSN PRBMDO; ISSN 0163-1829
Country of Publication:
United States
Language:
English