Abstract for 1999 American Vacuum Society Symposium

Interdiffusion During Growth of Ge on Si(100)

Authors:  Hannes Jonsson, Blas P. Uberuaga, Michael A. Leskovar, Brett R.
Schroeder, Shuang Meng and Marjorie A. Olmstead

Abstract:

We present both experimental evidence and a theoretical explanation of
sub-monolayer Ge epitaxy on Si(100) interdiffusion to the 4th layer of the
Si substrate. XPD measurements at both 500 C and 700 C show the presence
of Ge atoms in the 4th layer. DFT/GGA calculations of the energetics of a
Ge atom in the Si surface, together with a statistical model of Ge
occupation of the lattice sites, predict occupation of sub-surface sites,
with enhanced occupation in the sites under tensile strain. The
calculations indicate that the formation energy of a Ge interstitial near
the surface (about 1 eV higher energy than the adatom) is significantly
reduced as compared with an interstitial in bulk Si, thus lowering the
energy barrier for the interstitial diffusion mechanism near the surface.
This work was supported by the National Science Foundation, the University
of Washington Royalty Research Fund and the Japanese New Energy and
Technology Development Organization.