Intermixing at Ge/Si(001) interfaces studied by surface energy loss of medium energy ion scattering

Intermixing of Ge(0.15 ML, 1 ML)/Si(001) grown at 400 degrees C was studied by a new method of surface energy loss spectroscopy of medium energy ion scattering. We measured the inelastic energy losses of scattered ions from Ge for 100.0 keV H+ incidence as a function of exit angle. In the previous work for 50 and 100 keV H+ backscattered from the Si(001) 2 x 1-Sb surface [Phys. Rev. B in press], we showed that the surface stopping cross-section was expressed by extending the bulk stopping region from the top atomic plane toward the vacuum side by d, which was given by 2d rho=sigma (sigma is the areal density of top surface and rho is the bulk atomic density) as the first approximation. The above approximation uas applied to analysis of the Ge:/Si(001) interface. The present analysis revealed that the deposited Ge atoms were distributed over the first to third atom layers with a ratio of 4:3:1 or 4:2:2 for both 0.15 ML and 1 ML coverage. This result is consistent with that reported by Sasaki et al. [Appl. Surf. Sci. 82-83 (1994) 387] using Auger electron and X-ray photoelectron diffraction. (C) 1997 Elsevier Science B.V.