Experimental determination of the atomic structure of a H-terminated Si{111} surface

A Si{111}1×1-H surface is prepared by adsorbing atomic hydrogen on a freshly cleaved surface with the 2×1 structure. A quantitative low-energy electron diffraction analysis finds the following relaxations of the first four atomic layers: the first interlayer spacing is contracted by (9.3±3.8)%; the deeper spacings have bulk values within the experimental error. These results as compared with those of two published medium-energy ion-scattering experiments done on wet chemically prepared surfaces and are found to be in fair agreement with one and in disagreement with the other. Comparison with the first-principles calculations that have been reported in the literature in the recent past shows that our results are in good agreement with one and in fair agreement with two, but disagree beyond the estimated experimental error with two other such calculations. © 1995 The American Physical Society.