STRUCTURE OF A SI EPILAYER ON NI(100)

Silicon epilayers have been grown on a Ni{100}-p(1 X 1) substrate at 6 50 degrees C using an effusion cell. The deposited layers exhibit a c( 2 X 2) low energy electron diffraction (LEED) pattern. The structure o f the c(2 X 2)-Si epilayer was investigated by time-of-flight scatteri ng and recoiling spectrometry (TOE-SAPS) using 4 keV Kr+ ions to recoi l the Si and Ni atoms. The sharp anisotropy of Si recoil intensity as a function of crystal azimuthal angle (delta) demonstrates that the Si epilayer is ordered. The alignment of the azimuthal patterns of the S i and Ni recoils shows that the Si atoms occupy four-fold hollow sites on the Ni{100} surface. Plots of Si recoil intensity versus beam inci dent angle (alpha) for monolayer and fractional monolayer coverages ex hibit high sensitivity to Si defects. Classical ion trajectory simulat ions that have been used to model these alpha-scans allow interpretati on of the results in terms of direct and surface recoils. The height o f the Si epilayer above the four-fold hollow Ni sites, as determined f rom the agreement between the trajectory simulations and the alpha-sca ns, of 1.7 +/- 0.2 Angstrom gives a Si-Ni bond length of 2.5 Angstrom. TOF-SARS is demonstrated to be a viable technique for monitoring in s itu epitaxial film growth.