MEDIUM-ENERGY-ION-SCATTERING INVESTIGATIONS OF SI AND GE GROWTH ON GAAS(001)-C(2X8)/(2X4)

We have used high-resolution medium-energy-ion scattering, low-energy electron diffraction, x-ray photoemission spectroscopy, and cross-sectional transmission electron microscopy to investigate the growth of Ge and Si on GaAs(001)-c(2X8)/(2X4) at 490-degrees-C. In order to separately measure Ga, Ge, and As surface coverages, a Li+ ion beam was used to resolve the mass (69-76) isotopes involved. For the lattice-matched growth of Ge we observe high-quality epitaxial films with well-ordered interfaces. On the other hand, Si deposition creates films of uniform thickness but poor crystal quality, as well as a disordered Si/GaAs interface. In both cases, Ga and As segregate on the surface during growth. The supply of an external flux of Ga or As has a strong impact on interface and film morphology, as well as on the surface segregation of Ga and As.