Structure of a Si(100)2×2-Ga surface

Abstract

The 2X2 structure formed on a Ga-adsorbed Si(100) surface is determined using tensor low-energy electron diffraction. I-V curves of the parallel dimer model are in excellent agreement with those of the experiment, indicating that the actual surface has parallel dimer structure. Speci6c displacements of the topmost two surface layers (the protrusion of the Ga dimer toward the vacuum, the increase of the bond length of the Ga dimer, the stretching of the Si dimer, and the movement of the Si dimer toward the Ga dimer) with the elongation of the Si dimer back bond are observed in the optimized geometry. The Ga-Si bond angle measured from the Si(100) surface plane is recovered with these displacements from that of the ideal geometry where each bond length is assumed to be the sum of Pauling covalent radii. Subsurface layers are also deformed to keep the bond lengths near their bulk values.

Para to ortho transition of metallic dimers on Si(001)

“…The results for Ga and In also agree with recent experimental results obtained by Sakama et al 18,19 . The surface pattern at 0.5 ML coverage is 2×2.…”

“…We attempt to put the work in perspective and fill the holes by presenting new results. In particular, we find that our calculations at 0.5 ML give results in accord with Northrup's predictions and also with the recent experimental results obtained by Sakama et al 17,18,19 . More significantly, we obtain an orientational transition ('Para' to 'Ortho') for Al dimers as we go from 0.5 ML to 1 ML coverage.…”

“…All the experimental results 9,10,11,12,13,14,15,16,17,18,19,20 point to the fact that at low temperatures Al, Ga and In form 2×2 structure on the Si(001) surface at 0.5 ML coverage.…”

“…Low-energy-electron-diffraction (LEED), Auger electron spectroscopy (AES) and Scanning tunneling microscopy (STM) studies have provided much informations about the interaction of Al, Ga and In overlayers on the Si(001) surface at different coverages and at different temperatures 9,10,11,12,13,14,15,16,17,18,19,20 . Ide et al 9 observed 2×2, 2×3, 4×5, and 1×7 structures depending on the coverages less than 1 monolayer (ML) of Al on Si(001) and the substrate temperature in their LEED and AES experiments.…”

Atomic hydrogen induced gallium nanocluster formation on the Si(1 0 0) surface

“…These rows are constituted by gallium ad-dimers which are aligned parallel to the underlying silicon dimers [7][8][9]. Various sub-half monolayer reconstructions [10] are all formed by ad-dimer rows and differ from each other in the inter-row distances which are governed by repulsive interactions between these rows [7].…”