Surfactant-mediated growth of Ge/Si(001) studied by Raman spectroscopy andTEM

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.