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Modeling of Metal(100) Homoepitaxial Film Growth at Very Low Temperatures

Published online by Cambridge University Press:  10 February 2011

K.J. Caspersen ,
C.R. Stoldt ,
P.A. Thiel  and
J.W. Evans
K.J. Caspersen
Affiliation:
Departments of Chemistry and Mathematics, and Ames Laboratory, Iowa State University, Ames, Iowa 50011
C.R. Stoldt
Affiliation:
Departments of Chemistry and Mathematics, and Ames Laboratory, Iowa State University, Ames, Iowa 50011
P.A. Thiel
Affiliation:
Departments of Chemistry and Mathematics, and Ames Laboratory, Iowa State University, Ames, Iowa 50011
J.W. Evans
Affiliation:
Departments of Mathematics, and Ames Laboratory, Iowa State University, Ames, Iowa 50011
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Abstract

We model the growth of Ag films deposited on Ag(100) below 140K. Our recent Variable-Temperature Scanning Tunneling Microscopy (VTSTM) studies reveal “smooth growth” from 120-140K, consistent with earlier diffraction studies. However, we also find rougher growth for lower temperatures. This unexpected behavior is modeled by describing the deposition dynamics using a “restricted downward funneling” model, wherein deposited atoms get caught on the sides of steep nanoprotrusions (which are prevalent below 120K), rather than always funneling down to lower four-fold hollow adsorption sites. At OK, where no thermal diffusion processes are operative, this leads to the formation of overhangs and internal defects (or voids). Above 40K, low barrier interlayer diffusion processes become operative, producing the observed smooth growth by 120K. We also discuss how the apparent film morphology mapped out by the STM tip “smears” features of the actual film morphology (which are small at low temperature), and also can lead to underestimation of the roughness.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 619: Symposium L – Recent Developments in Oxide & Metal Epitaxy – Theory… , 2000 , 49
Copyright
Copyright © Materials Research Society 2000

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References

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