Surfactant-mediated growth and characterization of Ge(211)/Si(211) heterostructures grown by molecular beam epitaxy

We report the characterization of thin and thick Ge layers grown by molecul ar beam epitaxy on Si(2 1 1) substrates with and without As deposition prio r to Ge growth. The role of the As surfactant, as well as the dependence of the overall layer quality on the Ge growth rates and growth temperatures h as been studied. The Ge layer growth was monitored in situ by reflection hi gh-energy electron diffraction, and the Ge/Si heterostructures were charact erized ex situ by Raman spectroscopy. x-ray diffraction, and cross-sectiona l transmission electron microscopy. The results indicate that the growth mo de is altered significantly by saturating the Si surface with a monolayer o f As prior to initiation of Ge growth. Although Ge-Si interdiffusion and al loy formation on the Si(2 1 1) surface are dramatically reduced by nucleati ng Ge on Si with the aid of a surfactant, they are not completely suppresse d. A structural model for initiation of the surfactant-mediated growth is b riefly discussed. (C) 2001 American Vacuum Society.