THE ATOMIC STRUCTURE OF Si(111)-$(\sqrt{3}\times\sqrt{3})$R30°-Ga DETERMINED BY AUTOMATED TENSOR LEED

Abstract

The atomic structure of the Si (111)-[Formula: see text]R30°-Ga surface has been studied by comparing measured low-energy electron diffraction (LEED) intensity (IV) curves with calculated IV spectra using the method of automated tensor LEED. The experimental LEED IV curves used in this work contain many beams and a wide energy range. The results show that the Ga atoms occupy T4 sites, at 2.62 Å above the second-atomic-layer Si atoms. The Ga–Si vertical spacing is 1.44 Å and the bond length between the Ga atom and the first-layer Si atom is 2.52 Å. Large bucklings are found in the first and second Si bilayers below the adatom layer.