Verlag des Forschungszentrums Jülich
JUEL-3434
Wulfhekel, Wulf Carl Ulrik
Kinetic growth manipulation during molecular beam epitaxy
107 S., 1997
The growth of ultra thin films of Cu and Ni on Cu(111) as well as Si on Ge(100)
by molecular beam epitaxy is studied in-situ
with helium atom scattering (TEAS), LEED or STM.
During growth with constant deposition parameters at temperatures, where
the film structure is determined by kinetics and not thermodynamics,
in all three cases three-dimensional structures evolve.
Due to a hampered interlayer mass transport, nucleation of higher layer
islands sets in before the lower layers are completed.
Using the purely kinetic concept of two mobilities, layer-by-layer growth
in all three cases is obtained.
This concept is based on creating an artificially enhanced density of islands
during the early stage of monolayer growth such that nucleation on top of
these smaller islands is prevented up to the stage of coalescence.
However, details of the growth recipes have to be adjusted to the specific
kinetics of the system under investigation.
In case of Ni/Cu(111), interdiffusion limits the applicability of temperature
variation to enhance the island density.
In the case of Si/Ge(100), interlayer mass transport is hampered only at
double steps. Hence in this system, growth manipulation is adjusted to
avoid the formation of such steps.
By measuring the island density or other film properties as a function
of temperature or by direct observation of diffusion processes
with STM, different microscopic diffusion barriers are estimated.
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