Optical characterization of gold chains and steps on the vicinal Si(557) surface: Theory and experiment

Hogan, Conor; McAlinden, Niall; McGilp, J. F.

doi:10.1002/pssb.201100759

Cited by 10 publications

(7 citation statements)

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“…For this class of surfaces, it is known that the 1.5-3.0 eV negative structure derives from transitions involving Si honeycomb chains. The positive low energy feature instead has a more complicated character, being linked to various transitions associated with states delocalized along the Au chains and at the step edge dangling bonds [30,31]. The corresponding LEED pattern (see figure inset) reveals the presence of ×2 streaks, arising from the dimerization of the Au chains.…”

Section: B Optical Propertiesmentioning

confidence: 99%

“…Comparison of measured and calculated reflectance anisotropy spectra has been very helpful for identifying or discarding surface structural models [20]. RAS is particularly adept at distinguishing between similar quasi-1D surface reconstructions [29] and has previously been applied with success in the study of nominal Si(111)-Au and other vicinal Si(hhk)-Au systems [26,[30][31][32]. We thus carried out new experimental measurements of the RAS spectra of Si(775)-Au for different gold coverages and compared with calculations for the most stable models predicted in the previous section.…”

Section: B Optical Propertiesmentioning

confidence: 99%

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Si(775)-Au atomic chains: Geometry, optical properties, and spin order

Braun

Hogan

Chandola

et al. 2017

Phys. Rev. Materials

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The geometry and electronic structure of self-assembled atomic scale Au wires on Si(775) are investigated within density functional theory. The calculated surface diagram indicates the existence of two stable configurations with Au coverages of 0.32 and 0.96 monolayers, respectively. The low-coverage structure is predicted to host an antiferromagnetic spin chain localized at the Si rest atom dangling bonds, while the high-coverage structure is characterized by a Au-induced β-√ 3-like structure on the terrace. These structural models are supported by the comparison of measured and calculated surface optical anisotropies.

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Section: B Optical Propertiesmentioning

confidence: 99%

Section: B Optical Propertiesmentioning

confidence: 99%

Si(775)-Au atomic chains: Geometry, optical properties, and spin order

Braun

Hogan

Chandola

et al. 2017

Phys. Rev. Materials

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“…Indium atoms on Si(111) form NWs with a metallic character, [30][31][32][33][34][35][36][37] but also on high-index surfaces, such as Si(557), atomic wires are observed. 38 This is similar to Au, which preferentially forms chains on the high-index surfaces like Si(553) 17,20,[39][40][41] and Si(557) 20,25,40,[42][43][44][45][46] . Also Pb on Si(557) gives rise to conducting NWs, with quasi-1D states below a critical temperature of 78K; above this critical temperature the two dimensional (2D) coupling of the NWs makes the Pb chains 2D conducting.…”

Section: Introductionmentioning

confidence: 99%

Modeling 1D structures on semiconductor surfaces: synergy of theory and experiment

Vanpoucke

2014

J. Phys.: Condens. Matter

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Atomic scale nanowires attract enormous interest in a wide range of fields. On the one hand, due to their quasi-one-dimensional nature, they can act as a experimental testbed for exotic physics: Peierls instability, charge density waves, and Luttinger liquid behavior. On the other hand, due to their small size, they are of interest for future device applications in the micro-electronics industry, but also for applications regarding molecular electronics. This versatile nature makes them interesting systems to produce and study, but their size and growth conditions push both experimental production and theoretical modeling to their limits. In this review, modeling of atomic scale nanowires on semiconductor surfaces is discussed focusing on the interplay between theory and experiment. The current state of modeling efforts on Pt-and Au-induced nanowires on Ge (001) is presented, indicating their similarities and differences. Recently discovered nanowire systems (Ir, Co, Sr) on the Ge(001) surface are also touched upon. The importance of scanning tunneling microscopy as a tool for direct comparison of theoretical and experimental data is shown, as is the power of density functional theory as an atomistic simulation approach. It becomes clear that complementary strengths of theoretical and experimental investigations are required for successful modeling of the atomistic nanowires, due to their complexity.

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“…Surface energies were checked using the Perdew-Burke-Ernzerhof functional modified for solids (PBEsol) [30] within the projector-augmented-wave method [31]. Although relativistic pseudopotentials are used for Au, spin-orbit coupling is neglected, as its effect on RAS has been shown to be minor (mostly causing some broadening) [23,32]. Further details of the approach can be found elsewhere [32].…”

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confidence: 99%

“…Although relativistic pseudopotentials are used for Au, spin-orbit coupling is neglected, as its effect on RAS has been shown to be minor (mostly causing some broadening) [23,32]. Further details of the approach can be found elsewhere [32]. Constant current STM images are computed from the local density of states using the Tersoff-Hamann approximation [33].…”

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confidence: 99%

Optical Fingerprints of Si Honeycomb Chains and Atomic Gold Wires on the Si(111)-(5×2)-Au Surface

Hogan

Ferraro²,

McAlinden

et al. 2013

Phys. Rev. Lett.

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The intensively studied Si(111)-(5 Â 2)-Au surface is reexamined using reflectance anisotropy spectroscopy and density functional theory simulations. We identify distinctive spectral features relating directly to local structural motifs such as Si honeycomb chains and atomic gold wires that are commonly found on Au-reconstructed vicinal Si(111) surfaces. Optical signatures of chain dimerization, responsible for the observed (Â 2) periodicity, are identified. The optical response, together with STM simulations and first-principles total-energy calculations, exclude the new structure proposed very recently based on the reflection high-energy electron diffraction technique analysis of Abukawa and Nishigaya [Phys. Rev. Lett. 110, 036102 (2013)] and provide strong support for the Si honeycomb chain with the triple Au chain model of Erwin et al. [Phys. Rev. B 80, 155409 (2009)]. This is a promising approach for screening possible models of complex anisotropic surface structures. DOI: 10.1103/PhysRevLett.111.087401 PACS numbers: 78.68.+m, 73.20.Àr, 78.20.Bh The Si(111)-(5 Â 2)-Au surface has been the subject of long and intensive experimental and theoretical study, due to its potential for applications in nanoelectronics and its prototypical nature for studying self-assembly and properties of one-dimensional quantum structures [1,2]. On the experimental side, this includes STM [3][4][5], reflection high-energy electron diffraction (RHEED) [6], LEED [7], photoemission [8][9][10], and optical spectroscopy [11,12]; theoretical works generally focus on surface energies, electronic structure, and STM simulations [13][14][15][16]. Nonetheless, its structure remains controversial. Significant inconsistencies arose when even the most promising structures, all of which feature a Si honeycomb chain [17], were compared with experimental data [5].The recalibration in 2009 [18] of the Au coverage from 0.4 monolayers (ML) to 0.6 ML prompted a reevaluation of the Si(111)-(5Â2)-Au atomic structure. In particular, an exhaustive theoretical-experimental study by Erwin-Barke-Himpsel [16] (henceforth, EBH) proposed a three-chain model that largely resolved the remaining discrepancies in the STM and photoemission data [5]. However, a recent RHEED study by Abukawa and Nishigaya [6] (henceforth, AN) predicted a completely new structure, which appears consistent with Y-shaped structures found in STM [3,5]. Most notably, the model does not contain Si honeycomb chains.Independent evaluation of competing structural models is provided by reflectance anisotropy spectroscopy (RAS) [19]. The technique probes both filled and empty surface and interface states while discriminating against the bulk response of cubic materials and hence is particularly sensitive to the local surface and interface atomic structure. Moreover, RAS simulation has now evolved to a level capable of producing impressive agreement with experiment, revealing sensitivity to subtle structural phenomena, such as dimer composition [20] [26] in interface systems. Adsorbaterecon...

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Optical characterization of gold chains and steps on the vicinal Si(557) surface: Theory and experiment

Cited by 10 publications

References 48 publications

Si(775)-Au atomic chains: Geometry, optical properties, and spin order

Si(775)-Au atomic chains: Geometry, optical properties, and spin order

Modeling 1D structures on semiconductor surfaces: synergy of theory and experiment

Optical Fingerprints of Si Honeycomb Chains and Atomic Gold Wires on the Si(111)-(5×2)-Au Surface

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