Are bare surfaces detrimental in epitaxial growth?

For growth of epitaxial silicon-germanium structures by hydride chemical vapor deposition (CVD), the growth front is hydrogen-stabilized. Using medium energy ion scattering to examine the abruptness of an embedded Ge film in a Si(001) host, intermixing can be directly assessed. We have explored CVD films grown with varying hydrogen coverages, and find that adsorbed hydrogen serves a beneficial role in maintaining the abruptness of the interface. Embedded layers grown by molecular beam epitaxy are also more abrupt when the surface is stabilized, in this case by an adsorbed passivant such as Sb or As. Growth in the presence of a surface active agent (surfactant) results in greater control of constituents with no loss of epitaxial quality.