A study of atomic vibrations on Si(001)(2x1)-Ge
To be published in Applied Surface Science (1997)
Semiconductor Physics Group, Department of Physics, University of
Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom
We
have studied the surface dynamics of Si(001)(2x1)-Ge within an
adiabatic bond-charge model, the necessary structural and electronic
input information coming from a recent ab initio
pseudopotential calculation. The phonon spectrum of the
Si(001)(2x1)-Ge surface is compared in detail with that of the
Si(001)(2x1) surface presented in a recent bond-charge model study.
We observe that the growth of Ge upon the Si(001)(2x1) causes some
surface phonon energies to drop by up to 6 meV due to the large mass
difference between Ge and Si. We also present a comparison of the
phonon density of states of both surfaces and find that the growth of
Ge upon the Si(001)(2x1) surface leads to new peaks in the density of
states spectrum. Most notably, a strong peak in the lower energy tail
of the bulk continuum constitutes a distinct signature of the Ge
adlayer.
Stephen Jenkins
Last modified: Wed Jul 30 13:40:19 BST 1997