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Mechanisms of Mound Coarsening in Unstable Epitaxial Growth

Published online by Cambridge University Press:  10 February 2011

Jacques G. Amar
Jacques G. Amar*
Affiliation:
Department of Physics & Astronomy, University of Toledo, Toledo, OH 30322
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Abstract

The effects of various island and mound relaxation mechanisms on the mound morphology and asymptotic mound coarsening exponent n are investigated for growth on fcc/bcc(001) and fcc (111) metal surfaces. While the strength of the diffusion bias (due for example to an Ehrlich-Schwoebel step barrier) affects the crossover time, the presence or absence of corner diffusion is found to play a crucial role in determining the asymptotic value of the coarsening exponent. In the absence of island-relaxation or in the case of island-relaxation without rapid corner diffusion the asymptotic exponent is found to satisfy n ≃ 1/4. However, when rapid corner-diffusion is allowed, the coarsening exponent is found to approach 1/3. For the case of reversible island growth a strong step-barrier leads to an effective corner diffusion so that a growth exponent of either 1/4 or 1/3 may be observed depending on the strength of the step-barrier. These results appear to account for recent experimental observations of a large coarsening exponent (n ≃ 0.33) in epitaxial growth of Rh/Rh(111) at high temperature as well as of a smaller coarsening exponent (n ≃ 1/4) observed in epitaxial growth of Fe/Fe(001) and Cu/Cu(001). An explanation for these results is also presented in terms of the effects of corner diffusion on the surface current and mound morphology.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 570: Symposium V – Epitaxial Growth , 1999 , 11
Copyright
Copyright © Materials Research Society 1999

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References

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