Channeling Study of Epitaxial Aluminium and Silver Films on Si(111) Substrates

Aluminum films formed by the ion cluster beam deposition (ICBD) and Ag films formed by molecular beam epitaxy deposition on Si(111) substrates were studied by MeV ion channeling techniques. Both the Al and Ag films were found to be epitaxial, despite their large lattice mismatch to Si substrates (both are close to 25%). Both the Al and Ag films were found to contain dislocation loops, which is attributed to the large lattice mismatch. Displaced Al atoms in the Al film but no displaced Ag atoms in the Ag films were found. The existence of displaced Al atoms is attributed to the bombardments of ion or ionized clusters in ICBD. A large step increase in dechanneling at the Al/Si interface was observed, which decreases with the increasing incident energy. The existence of a "semicoherent" interface in which four Al lattice planes match three Si lattice planes almost perfectly cannot explain the energy dependence of the step increase. The thickness of the Ag films was found to have an obvious effect on the epitaxial growth. A misoriented growth of the Ag film was also observed. Spectra, graphs. 14 ref.--AA(UK).