Growth of Thin Ti Films on Al Single-crystal Surfaces
at Room Temperature
R.J. Smith, Y.W. Kim, N.R. Shivaparan, G.A. white, M.A. Teter,
Department of Physics, Montana State University, Bozeman, Montana 59717*
The growth of thin Ti films on Al(001), Al(110) and Al(111) surfaces
at room temperature has been studied using high-energy ion backscattering
(RBS) and channeling, x-ray photoemission (XPS), and low-energy electron
diffraction (LEED). Our results show that Ti atoms form a thin, metastable,
fcc overlayer on Al(110) and Al(001) surfaces. The primary evidence
for this conclusion is the reduced backscattering which occurs as the Ti
atoms shadow the Al atoms in the fcc structure of the Al substrate.
For the Al(111) surface the Al surface peak area in ion channeling, measured
as a function of Ti coverage, shows a small decrease for the first monolayer
(ML) of Ti coverage, but then increases gradually with coverage, a characteristic
of alloy formation. However, XPS and LEIS results are generally consistent
with overlayer growth of Ti on the Al(111) surface, and the LEED pattern
indicates an ordered overlayer for Ti coverages from 2 to 12 ML, at which
point the Al surface was completely covered by Ti. The results suggest
the growth of incommensurate, ordered islands of hcp Ti on Al(111) in an
SK growth mode, in remarkable contrast to the pseudomorphic fcc Ti overlayer
growth observed for Ti films on Al(001) and Al(110).
*Work supported by NSF Grant No. DMR-9710092 and NASA EPSCoR Grant NCCW-0058
Surface and Interface Analysis 27, 185-193
(1999)
For information on this publication or to request
a reprint send mail to smith@physics.montana.edu
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