GROWTH MODE OF GE FILMS ON SI(100) SUBSTRATE DEPOSITED BY ION-BEAM SPUTTERING

Germanium thin films have been grown on silicon(100) substrates by ion beam sputter deposition (IBSD) in an ultrahigh vacuum system. The gro wth mode of the films as a function of the growth temperature and the ion incidence angle was investigated by in situ Auger electron spectro metry. The morphology of the film surface was examined by scanning ele ctron microscopy. The effect of the deposition temperature on the inte rface roughness was investigated after selectively etching the Ge film . We have found that the growth mode of IBSD-Ge on silicon does not ag ree with a layer-by-layer growth. The decay of the Si signal as the gr owth proceeds may be interpreted in terms of either a Stransky-Krastan ov growth mode with island formation after two-dimensional growth or S i segregation to the surface. We showed that IBSD leads to more abrupt interfaces than molecular beam epitaxy. This last result may be relat ed to the energetic bombardment of the film during deposition. To supp ort this model more quantitatively, computer calculations have been ca rried out by using an advanced version of the Monte Carlo ''transport of ions in matter'' code (TRIM).