Strain-induced lattice relaxation during overlayer growth is investigated by in situ monitoring of and growth on Si(111) with x-ray standing-wave fluorescence and low-energy electron diffracton. Submonolayer films show both intrinsic lateral disorder and variable interface stoichiometry with discommensuration parallel to the surface after completion of the first monolayer. In contrast, local commensuration is observed for Ca-rich alloy films. In the alloy, Sr and Ca occupy different sites in the first monolayer, but have similar average positions in subsequent layers.
- Received 24 September 1990
- Published in the issue dated 15 March 1991
© 1991 The American Physical Society