Photoelectron diffraction of the Si(111)-(3×3)R30°-Ga surface: Local atomic structureand vibrational correlation

Abstract

The kinetic-energy dependence of the polar-angle photoelectron diffraction of Ga 3d emission was measured on the Si(111)-()ϫ))R30°-Ga surface using synchrotron radiation. The energy-dependent variations in the polar-angle intensity distribution can be reproduced by model calculations essentially assuming one scattering Si atom 2.6 Å below the Ga photoelectron emitter. This fact clearly indicates that the Ga atom adsorbs at the site directly above a second-layer Si atom ͑T 4 site͒. Calculations of the photoelectron diffraction using larger clusters have revealed that the vibrational correlation between the Ga adatom and the Si atom directly below it is very strong. This correlation effect emphasize the scatterings by the Si atom directly below the emitter compared with those by other surrounding atoms.

Evolution of surface morphology of vicinal Si(111) surfaces after aluminum deposition

“…However, the assuming A3(sh)2, which suggests that the stress term is dominant. Also, as tabulated and discussed stress of (ǰ3×ǰ3)R30°Ga on this substrate -which has the same T 4 adsorption site and similar for lattice parameters since, at room temperature, the steps apparently are quantized in terms of the local geometry (though a different-symmetry (3×2) reconstruction, while even the (3×1) has bonding orbital ) [44] -has been found theoretigone at the ''freezing'' temperature of the Si(113) cally, using ab-initio pseudopotentials, to be 1.4 eV steps [48] that is presumed to mark the equilibraper (1×1) cell, somewhat less than the values of tion point of the observed distributions [23,24]. 1.66 for (2×2) Si(111) or 1.70 for (ǰ3×ǰ3)R30°I n any case, there is no evidence that anything Si(111) [41,45].…”

Gallium structure on the Si(111)-(7 × 7) surface: influence of Ga coverage and temperature

“…Hence, the understanding of the behaviour of Ga on Si surfaces at different temperatures and a wide range of coverages is a very important issue. Gallium superstructures on the Si(111)-(7 × 7) surface (coverages up to 1 ML) have already been studied mostly by such methods as low energy electron diffraction [3], the x-ray standing-wave technique [4,5,7], scanning tunnelling microscopy [5][6][7][8][9][10], electron energy loss spectroscopy [11], and photoelectron diffraction [12].…”

“…For a coverage of 1/3 ML of Ga and deposition (annealing, respectively) temperature 550 • C, the ( √ 3 × √ 3) R30 • surface reconstruction was found. Gallium atoms (sp 3 hybridization) occupy half of the fourfold coordinated T 4 sites [3,5,12] and completely terminate all the silicon surface dangling bonds.…”

Ga-induced superstructures on the Si(111) 7×7 surface

“…Thus growing stable superstructures of Ga on Si surfaces and the possibility of nitriding them promises usable forms of GaN nanostructures with novel properties. Ga superstructures have been studied extensively by low energy electron diffraction (LEED) [7], X-ray standing wave (XSW) [8], electron energy loss spectroscopy (EELS) [2] and photoelectron spectroscopy (PES) [9]. However, since the structure and properties of the overlayers depend strongly on the kinetics of growth, more systematic and careful studies are required to tailormake systems that give the desired properties.…”