Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Growth of epitaxially oriented Ag nanoislands on air-oxidized
  Si(111)-(7x7) surfaces: Influence of short range order on the substrate   Clean Si(111)-(7{x7) surfaces, followed by air-exposure, have been
investigated by reflection high energy electron diffraction (RHEED) and
scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images
show the presence of short range (7x7) order on the air-oxidized surface.
Comparison with FTs of STM images from a clean Si(111)-(7x7) surface shows that
only the 1/7th order spots are present on the air-oxidized surface. The oxide
layer is ~ 2-3 nm thick, as revealed by cross-sectional transmission electron
microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(111)-(7x7)
surfaces has been investigated by in-situ RHEED and STM and ex-situ XTEM and
scanning electron microscopy. Ag deposition at room temperature leads to the
growth of randomly oriented Ag islands while preferred orientation evolves when
Ag is deposited at higher substrate temperatures. For deposition at 550{\deg}C
face centered cubic Ag nanoislands grow with a predominant epitaxial
orientation [1 -1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si along with its twin
[-1 1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si, as observed for epitaxial growth
of Ag on Si(111) surfaces. The twins are thus rotated by a 180{\deg} rotation
of the Ag unit cell about the Si [111] axis. It is intriguing that Ag
nanoislands follow an epitaxial relationship with the Si(111) substrate in
spite of the presence of a 2-3 nm thick oxide layer between Ag and Si.
Apparently the short range order on the oxide surface influences the
crystallographic orientation of the Ag nanoislands.

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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
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The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
2
The categories of this paper are: math
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The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph