Interface structure of epitaxial Ge–Si(111) system studied by high energy ion scattering

We have applied MeV ion scattering to a study of the initial stage of heteroepitaxy of the Ge on Si(111) system and shown that the Ge film deposited at 350 °C grows epitaxially without interfacial mixing; the growth mode of this system is of the Stranski–Krastanov type; the interface atomic structure is pseudomorphic at first, i.e., the first ∠3 monolayers of Ge are registered to the Si strings within ∠0.1 Å, after which expansion of the Ge overlayer occurs introducing strains at the interface. From this point on it is probable that the germanium film is highly defected. After deposition of about 20 monolayers of germanium the interface appears to be stable with ∠4 monolayers of strain on the Si crystal side and more than 10 monolayers of net distortion on the Ge side.