Refinement of the (111) × -Ag structure by surface X-ray diffraction

Takahashi, Toshio; Nakatani, Shinichiro

doi:10.1016/0039-6028(93)90607-l

Cited by 149 publications

(46 citation statements)

References 40 publications

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“…1(d)]. 10,11 The adsorbed Ag atoms form covalent bonds with the substrate Si atoms, leaving no dangling bonds on the surface. Thus an , (e) Two-dimensional band-dispersion diagrams of surface states determined by angle-resolved ultraviolet photoelectron spectroscopy (ARUPS).…”

Section: Introductionmentioning

confidence: 99%

Surface Electrical Conduction Correlated with Surface Structures and Atom Dynamics

et al. 1998

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By utilizing a variety of surface superstructures formed on silicon surfaces, we have clarified close correlations between the atomic-scale structures and surface-electrical-conduction phenomena. In particular, we have succeeded for the first time in experimentally confirming the electrical conduction via surface-state bands that are inherent in the surface supertructures. Also, an important phenomenon has been found: atoms adsorbed on the surface donate carriers to the surface-state band, resulting in a remarkable enhancement of conductivity. The ultimate two-dimensional electron systems composed of surface-state bands, which are made close up in our study, are expected to provide a new stage in surface physics.

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Section: Introductionmentioning

confidence: 99%

Surface Electrical Conduction Correlated with Surface Structures and Atom Dynamics

et al. 1998

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“…We did the calculation by adopting two kinds of models of atomic arrangement for the Si(111) √ 3 × √ 3-Ag structure, the honeycomb-chained triangle (HCT) model [18], Fig. 3(a), and the inequivalent-triangle (IET) model [19], Fig.…”

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confidence: 99%

Photoemission Structure Factor Effect for Fermi Rings of the Si(111)√3×√3-Ag Surface

Hirahara

Matsuda

Hasegawa

2004

e-J. Surf. Sci. Nanotechnol.

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The energy contour at Fermi level (Fermi surface) of the Si(111) √ 3 × √ 3-Ag superstructure was measured in several surface Brillouin zones (SBZs) by high resolution angle-resolved photoemission spectroscopy (ARPES). Fermi rings centered at Γ points were observed only in the second SBZs, but missing in the first SBZ. This phenomenon was successfully reproduced by a calculation of the optical transition matrix based on a simple tightbinding approximation for the surface topmost-layer Ag atoms; the intensity in the first SBZ is diminished by destructive interferences in the matrix elements (i.e., photoemission structure factor). Thus with the known atomic orbital components of the surface structure, we can predict the photoemission intensity distribution and correctly understand the band structure. [DOI: 10.1380[DOI: 10. /ejssnt.2004 Keywords: Angle-resolved photoemission spectroscopy; Fermi surface; Photoemission structure factor; Surface state; Band dispersion; Ag; Si Angle-resolved photoemission spectroscopy (ARPES) has been a powerful tool to determine electronic structures (band dispersion and Fermi surface) of a solid material, especially crystal surfaces. However, the technique often enables to detect the bands only in the limited (surface) Brillouin zones though the band structures should repeat in every Brillouin zone. In other cases the observed intensity distributions of band structures sometimes look asymmetric depending on the polarization of exciting light. These phenomena are in many cases due to k-dependent transition probability of electrons from the initial to the final states in the photoemission process. This complication sometimes raises discrepancies among researchers in the band structure determination. A solution for this issue is to record the photoemission intensity distribution across the full hemisphere for both polar and azimuthal emission angles covering several Brillouin zones [1][2][3]. This is owing to recent developments of bright excitation sources and high-resolution electron analyzers with parallel detectors.It is well known that ARPES measurements of the Si(111) √ 3 × √ 3-Ag surface, one of the most widely studied prototype of metal-on-semiconductor systems, show such a property. Previous ARPES studies revealed a parabolic surface-state band (S 1 band) crossing Fermi level, having a circular Fermi surface (Fermi ring) around Γ points. However, the rings were observed only in the second √ 3 × √ 3-surface Brillouin zones (SBZs), but not in the first SBZ [4][5][6][7][8][9][10][11][12]. It has been proposed that the phenomenon is originated from a coupling of the S 1 surface state with the bulk states of Si substrate crystal, because there is an overlap in energy-momentum space between the S 1 state and bulk states only in the first SBZ [9]. Here, we show another explanation for it in terms of the k-dependent transition probability, i.e., an interference effect in the matrix elements of optical transition, socalled photoemission structure factor (PSF) or Brillouinzone-selection e...

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“…It has the honeycomb-chained trimer (HCT ) structure [2][3][4], where the top layer of Ge-atoms are missing Over the last decade there has been a great effort and the remaining Ge-atoms in the outermost trying to understand the atomic geometry of metalbilayer form trimers which are surrounded by Ag induced reconstructions on elemental semiconducatoms, is similar to the structure of the tor surfaces. An example of such a system is Ag Si(111)-(ǰ3×ǰ3)R30°-Ag surface [5,6 ]. The on the Ge(111) surface.…”

Section: Introductionmentioning

confidence: 99%

Solution of Ge(111)-(4×4)-Ag structure using direct methods applied to X-ray diffraction data

et al. 1998

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A structure model for the Ge(111)-(4×4)-Ag surface is proposed. The model was derived by applying direct methods to surface X-ray diffraction data. It is a missing top layer reconstruction with six Ag atoms placed on Ge substitutional sites in one triangular subunit of the surface unit cell. A ring-like assembly containing nine Ge atoms is found in the other triangular subunit. The stability of the ring assembly may be due to Ge-Ge double bond formation. Trimers of Ge atoms, similar to the trimers found on the Ge(111)-(ǰ3×ǰ3)R30°-Ag surface, are placed in the corners of the unit cell.

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Refinement of the (111) × -Ag structure by surface X-ray diffraction

Cited by 149 publications

References 40 publications

Surface Electrical Conduction Correlated with Surface Structures and Atom Dynamics

Surface Electrical Conduction Correlated with Surface Structures and Atom Dynamics

Photoemission Structure Factor Effect for Fermi Rings of the Si(111)√3×√3-Ag Surface

Solution of Ge(111)-(4×4)-Ag structure using direct methods applied to X-ray diffraction data

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