IN-SITU SURFACE TECHNIQUE ANALYSES AND EX-SITU CHARACTERIZATION OF SI1-XGEX EPILAYERS GROWN ON SI(001)-2X1 BY MOLECULAR-BEAM EPITAXY

Si1-xGex epilayers grown by Molecular Beam Epitaxy on Si(001) at 400-d egrees-C have been analyzed in-situ by surface techniques such as X-ra y and Ultraviolet Photoelectron Spectroscopies (XPS and UPS), Low Ener gy Electron Diffraction (LEED) and photoelectron diffraction (XPD). Th e Ge surface concentrations (x) obtained from the ratios of Ge and Si core level intensities are systematically higher than those obtained b y the respective evaporation fluxes. This indicates a Ge enrichment in the first overlayers confirmed by Ge-like UPS valence band spectra. T he structured crystallographic character of the epilayers is ascertain ed by LEED and XPD polar scans in the (100) plane since the Ge Auger L MM and the Si 2p XPD intensity patterns from the Si1-xGex epilayers ar e identical to those of the Si substrate. The residual stress in the e pilayer is determined by ex-situ X-ray diffraction (XRD) which also al lows, as Rutherford Back Scattering (RBS), Ge concentration determinat ions.