STRUCTURE-ANALYSIS OF THE HF-TREATED SI(111)H SURFACE WITH MEDIUM-ENERGY ION-SCATTERING

Medium-energy ion scattering (MEIS) measurements have been performed o n the Si(111) surface which was terminated with hydrogen by means of i mmersion in a diluted HF solution. The measurements and the fit of Mon te Carlo simulations to the experimental data show that the structure of the Si(111):H surface is close to that of a truncated bulk Si latti ce. The relaxation of the distance between the top and the second laye r, d(12), and that between the second and the third layer, d(23) are a s small as 0.00+/-0.04 Angstrom (0.0+/-5.1%) and - 0.04+/-0.04 Angstro m ( - 1.7+/-1.7%), respectively. The measurements further reveal that the average one-dimensional root-mean-square thermal displacement of t he two outermost atomic layers is enhanced from the bulk value of 0.07 5 Angstrom to 0.11+/-0.01 Angstrom.