Structure of the quasi-one-dimensional Si(553)-Au surface: Gold dimer row and silicon honeycomb chain

Abstract

The Si͑553͒-Au surface consists of a periodic array of single steps and ͑111͒ terraces with a quasi-onedimensional electronic structure. In this paper, the determination of the atomic structure of this surface with x-ray diffraction is reported. The gold coverage of the surface was measured to be 0.5 monolayer using x-ray fluorescence spectroscopy, i.e., two gold atoms per primitive unit cell. A structural model was constructed directly from the x-ray diffraction intensities with a step-by-step approach. First, the relative positions of the gold atoms were obtained from the Patterson map. Using the positions of the gold atoms, the deconvolution of the Patterson map was calculated and the positions of the gold atoms relative to the substrate were determined. Finally, the positions of the silicon atoms at the surface were obtained from a reconstruction of the electron density with an iterative phase and amplitude recovery algorithm. The main features of the structural model obtained in this way are a row of gold dimers on the ͑111͒ terraces in the topmost layer of the surface, and a honeycomb chain of silicon atoms near the step edge. Structural refinement of this model with the experimental diffraction data gave reasonable atomic positions and a 2 value of 3.35, better than previous models. The model is related to the ϫ2 m1 model recently proposed by Krawiec ͓Phys. Rev. B 81, 115436 ͑2010͔͒ but without the strong ϫ2 modulation.

Structural and electronic properties of double Pb chains on the Si(553)-Au surface

“…The normal to this surface is tilted from the [111] direction toward [112] by 12.27 • . This surface has been studied by a number of techniques, including scanning tunneling microscopy (STM), [4][5][6][7][8][9][10][11][12] angle-resolved photoemission (ARPES), 4,5,7,10,13,14 x-ray diffraction, [15][16][17][18] and density functional theory (DFT). 4,[19][20][21][22] The STM topography of the Si(553)-Au surface reveals single several-nanometer-long chains on each terrace, which come from the step-edge Si atoms.…”

Identification of the Structure Model of theSi(111)−(5×2)−AuSurface

“…Structure determination is a necessary step for understanding the nature of a system, but in the case of these quasi-1D structures the structure analysis is not straightforward due to a large unit cell with a low symmetry and the incoherence in the chain-chain ordering. For the Si(111) vicinal surfaces, successful structure models were proposed by surface x-ray diffraction (SXRD) experiments [12,13]. However, the Sið111Þ-ð5 × 2Þ-Au structure still remains controversial, although more than a dozen structure models were proposed along with the development of surface science techniques [14][15][16][17][18][19][20][21][22][23][24][25][26].…”

“…The Sið111Þ-ð5 × 2Þ-Au structure was prepared by depositing Au on the Sið111Þ-ð7 × 7Þ clean surface at 730°C and postannealing at the same temperature for 10 min. The Au coverage was calibrated by ex situ x-ray fluorescence spectroscopy to be ∼0.6 ML [13], which falls within the range of others reported as 0.56-0.67 ML [32,33]. All the measurements were done at room temperature.…”

Two-dimensional interaction of spin chains in the Si(553)-Au nanowire system

“…STM simulations, however, seemed to be in good agreement with a single atomic Au row in the middle of the terrace 15,18 . Finally, diffraction experiments also gave strong favor to an Au coverage of 0.5 ML 19,20 . Well below room temperature electron diffraction patterns show a twofold (×2), and a threefold (×3) periodicity along the steps, respectively 12,19,21 .…”