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iABSTRACT The surface periodicity is broken in the
surface normal direction, i.e. , the z direction, as the result
of missing atoms on the vacuum side of the surface. This
interrupted periodicity creates broken bonds. In order to
minimize the surface free energy, the surface atoms rebond at
the cost of bond bending and stretching for most semiconductors.
As an example, the surface atoms rebond to form dimers on the
Si(001) surface. This surface atom rebonding, or
reconstruction, generates anisotropic surface stresses in
inequivalent crystallographic directions. This stress
anisotropy plays a crucial role in determining the surface
morphology. When Ge atoms are deposited on a Si(001)
surface, the mismatch-induced stress has crucial influences on
the initial growth of Ge film due to the rather large lattice
mismatch of 4.3% between Si and Ge. The observed 2*N overlayer
structure consists of rebonded missing dimer rows which are
responsible for the relief of the overlayer stress resulting
from the lattice mismatch. We have used Low Energy
Electron Diffraction (LEED) to investigatethe Ge/Si(001) surface
under externally applied stress. We have utilized the AVMJ[6]
theory to calculate the surface stress anisotropy for different
Ge coverages. We have also studied other surface properties
such as the diffusion kinetics of surface atoms.
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