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

Abstract

The atomic structure of the Si(111)-(5 × 2)-Au surface, a periodic gold chain on the silicon surface, has been a long-debated issue in surface science. The recent three candidates, the so-called Erwin-Barke-Himpsel (EBH) model [S. C. Erwin, I. Barke, and F. J. Himpsel, Phys. Rev. B 80, 155409 (2009)], the Abukawa-Nishigaya (AN) model [T. Abukawa and Y. Nishigaya, Phys. Rev. Lett. 110, 036102 (2013)], and the Kwon-Kang (KK) model [S. G. Kwon and M. H. Kang, Phys. Rev. Lett. 113, 086101 (2014)] that has one additional Au atom than the EBH model are tested by surface x-ray diffraction data. A two-dimensional Patterson map constructed from the in-plane diffraction intensities rejects the AN model and prefers the KK model over the EBH model. On the basis of the arrangement of Au obtained from the Patterson map, all the reconstructed Si atoms, such as the so-called honeycomb chain structure, are directly imaged out by utilizing a holographic method. The KK model reproduces out-of-plane diffraction data as well.

Vibration eigenmodes of the Au- (5×2) /Si(111) surface studied by Raman spectroscopy and first-principles calculations

“…Altogether, the present calculations for the KK model agree considerably better with the measured data than the calculations based on the EBH structure. The preference for the KK model is in agreement with experimental results from surface x-ray diffraction [10], infrared spectroscopy [11], and reflectance anisotropy spectroscopy [14].…”

“…A possible realization is the material system Au/Si(111), where, depending on the Au coverage and the substrate temperature, one-or two-dimensional ordered Au patterns can be achieved, whose reconstructions are characterized by the (5 × 2) and ( √ 3 × √ 3) periodicity, respectively [2,3]. The Au-(5 × 2)/Si(111) reconstruction with its onedirectional Au-induced chains has been the subject of extended experimental and theoretical investigations [4][5][6][7][8][9][10][11] for many years. In spite of all these studies, the atomic arrangement of this reconstruction has given rise to recent disputes in the literature.…”

“…The latter model will be referred to as the KK model. It was favored by several recent studies, employing surface-x-ray diffraction [10], DFT calculations of the core-level shifts in x-ray photoemission spectroscopy (XPS) [13], and comparative hybrid DFT calculations of atomic structure, electronic band structure, and reflectance anisotropy [14]. Furthermore, it should also be noted that the equilibrium surface has ≈0.025-ML coverage of Si adatoms, divided into structural domains without adatoms and domains with ≈0.05-ML Si adatom coverage.…”

Raman Spectroscopy on Surface Phonons of Si(hhk) Surfaces Modified by Au Submonolayers

“…This yields a more favorable energy, an improved compatibility to the scanning tunneling microscopy (STM) images, and an intrinsic (5 × 2) periodicity. The KK model was favored by surface‐X‐ray diffraction, DFT calculations of the core‐level shifts in X ray photoemission spectroscopy (XPS), and comparative hybrid DFT calculations of atomic structure, electronic band structure, and Reflectance Anisotropy . Furthermore, it should also be noted that the equilibrium surface additionally has an ≈0.025 ML coverage of Si adatoms, divided into structural domains without adatoms and domains with ≈0.05 ML Si adatom coverage, as was verified by several research groups …”

“…The signature elements of the‐Au (5 × 2) reconstruction on the nominal Si(111) surface are one‐directional Au‐induced chains as shown in Figure (b) which have been subject of the extended experimental and theoretical investigations since many years . A model established by Erwin, Barke, and Himpsel (EBH model) is based on a Au coverage of 0.6 ML, resulting in a surface unit cell consisting of 6 Au atoms and 12 top‐layer Si‐atoms, which leads to an arrangement of Au triple chains and Si honeycomb chains .…”