Alloy formation at the Ni-Al interface for Ni films deposited
on Al(110) surfaces
V.Shutthanandana, Adli A. Saleh, and R. J. Smith,
Department of Physics, Montana State University, Bozeman, Montana 59717*
Alloy formation at the Ni-Al interface for thin Ni films deposited
on Al(110) surfaces has been studied using high-energy ion scattering/channeling
(HEIS) and x-ray photoelectron spectroscopy (XPS). For Ni atoms deposited
at room temperature on Al(110) a large amount of Ni-Al intermixing occurs
at the interface. For the first two monolayers (ML) of deposited
Ni, a NiAl-like compound is formed. The intermixing continues with
a different rate, forming a Ni3Al-like compound for Ni coverages from 2
to 8 ML, at which point a Ni metal film begins to grow on the surface.
Nickel atoms deposited at 250 C on the Al(110) surface exhibit no surface
compound formation, but diffuse up to 400Å into the Al substrate.
Interatomic potentials based on the embedded atom method (EAM) are used
in a Monte Carlo approach to simulate the evolution of the Ni-Al(110) interface
as a function of the Ni coverage. The calculated ion scattering yields
and x-ray photoelectron intensities from Ni and Al atoms in these simulated
interfaces are in good quantitative agreement with the experimental results.
The simulations show a high-density Ni-Al alloy forming at the Al(110)
surface which apparently inhibits outward diffusion of Al, leading to the
more Ni-rich alloy and finally Ni film growth. The ion scattering
simulations show an unusually large amount of backscattering occurring
below the Ni-Al(110) interface, apparently associated with defocusing of
the incident ion beam.
*Work supported by NSF Grant No. DMR-9710092 and NASA EPSCoR Grant NCCW-0058
Submitted for publication (1999)
For information on this publication or to request
a reprint send mail to smith@physics.montana.edu
Return to the Ion Beams Publication
List
Return to the Ion Beams Home
Page
Page Maintained by Dick Smith Send
mail to Smith@physics.montana.edu