Growth of Ge/Si follows the Stranski-Krastanov growth mode (2D --> 3D) beca
use of the 4.2% lattice mismatch between Ge and Si. However, the growth mod
e can be altered to Frank-Van der Merwe (layer-by-layer) by depositing a su
itable surfactant. In this study, we have grown thin and thick Ge(0 0 1)/Si
(0 0 1) MBE layers with and without As deposition prior to Ge growth in ord
er to investigate the details of surfactant-mediated epitaxy. Raman spectro
scopy shows that without As surfactant use, Ge and Si interdiffuse at the i
nterface and form an alloy, Furthermore, peak shift measurements as well as
cross-sectional electron micrographs reveal that layers grown with As slow
ly relieve misfit strain through the accommodation of Lomer edge dislocatio
ns at the interface leaving a relaxed, nearly defect-free layer. (C) 1999 E
lsevier Science B.V. All rights reserved.