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 conjugation in the epitaxial Si(111)-
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 surface: Unconventional “bamboo hat” bonding geometry for Si

Jiang, Wei; Liu, Zheng; Zhou, Miao; Ni, Xiaojuan; Liu, Feng

doi:10.1103/physrevb.95.241405

Cited by 6 publications

(6 citation statements)

References 43 publications

(62 reference statements)

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“…We conducted DFT calculations on high Miller index surfaces {557}, {335}, and {334}, alongside two low Miller index surfaces {100} and {111} of Si, as illustrated in the HRTEM images (Figure D and E) (Figure A). Simulations of surface structure relaxation indicated extensive reconstruction on all H-passivated high Miller index surfaces, with the commonly reported (2 × 1) “Pandey-chain” surface reconstruction emerging along the {111} terraces. − For instance, the {557} surface of Si consists of six sequential surface units of the {111} surface along the terrace punctuated by a single unit of the {100} surface at the step. When combined with hydrogen passivation, these reconstructions effectively eliminate surface dangling bonds, reinstating a semiconducting bandgap between 1.15 and 1.37 eV and yielding energy stabilization between 0.54 and 1.14 eV/H atom for the {557}, {335}, and {334} surfaces (Figure S11).…”

Section: Results and Discussionmentioning

confidence: 80%

Nontypical Wulff-Shape Silicon Nanosheets with High Catalytic Activity

Lee,

Kim,

Jang

et al. 2023

J. Am. Chem. Soc.

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Nanostructured silicon with an equilibrium shape has exhibited hydrogen evolution reaction activity mainly owing to its high surface area, which is distinct from that of bulk silicon. Such a Wulff shape of silicon favors low-surface-energy planes, resulting in silicon being an anisotropic and predictably faceted solid in which certain planes are favored, but this limits further improvement of the catalytic activity. Here, we introduce nanoporous silicon nanosheets that possess high-surface-energy crystal planes, leading to an unconventional Wulff shape that bolsters the catalytic activity. The high-index plane, uncommonly seen in the Wulff shape of bulk Si, has a band structure optimally aligned with the redox potential necessary for hydrogen generation, resulting in an apparent quantum yield (AQY) of 12.1% at a 400 nm wavelength. The enhanced light absorption in nanoporous silicon nanosheets also contributes to the high photocatalytic activity. Collectively, the strategy of making crystals with nontypical Wulff shapes can provide a route toward various classes of photocatalysts for hydrogen production.

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Section: Results and Discussionmentioning

confidence: 80%

Nontypical Wulff-Shape Silicon Nanosheets with High Catalytic Activity

Lee,

Kim,

Jang

et al. 2023

J. Am. Chem. Soc.

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“…It is known for its completely quenched kinetic energy and can be generally categorized into two classes, i.e., localized state and itinerant state with destructive interference. The localized states are common but typically trivial, which can be viewed as isolated states without interaction, such as dangling bond or the defect state in semiconductors [15][16][17] . The flat bands formed by destructive interference are quite rare, which normally have stringent symmetry and coupling requirement, such as in the 2D Kagome 18 , Lieb 19 and most recently discovered coloring-triangle (CT) 20 lattices.…”

Section: Introductionmentioning

confidence: 99%

Topological band evolution between Lieb and kagome lattices

et al. 2019

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Among two-dimensional lattices, both Kagome and Lieb lattices have been extensively studied, showing unique physics related to their exotic flat and Dirac bands. Interestingly, we realize that the two lattices are in fact interconvertible by applying strains along the diagonal direction, as they share the same structural configuration in the unit cell, i.e., one corner-site and two edge-center states. We study phase transitions between the two lattices using the tight-binding approach and propose one experimental realization of the transitions using photonic devices. The evolution of the band structure demonstrates a continuous evolution of the flat band from the middle of the Lieb band to the top/bottom of the Kagome band. Though the flat band is destroyed during the transition, the topological features are conserved due to the retained inversion symmetry, as confirmed by Berry curvature, Wannier charge center, and edge state calculations. Meanwhile, the triply degenerate Dirac point (M ) in the Lieb lattice transforms into two doubly degenerate Dirac points with one of which moves along M -Γ and the other moves along M -K/K directions that form the Kagome band eventually. Interestingly, the Dirac cones in the transition states are strongly tilted, showing a coexistence of type-I and type-II Dirac points. We finally show that these transitions can be experimentally realized in photonic lattices using waveguide arrays.

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“…[29] Therefore the TDB (111) surface is not considered in most of the reports in the literature. [30,31] Consequently, to circumvent the dangling bonds inconsistency of the (111) surface as mentioned above, a rough effect of surface reconstruction is taken into consideration. During dangling bonds counting, two kinds of TDB surface are seen.…”

Section: Methodsmentioning

confidence: 99%

“…However, even after reconstruction, the TDB surface energy is still higher than that of the SDB surface, due to the formation of weaker π-bonds at the TDB surface than those at the SDB surface [29]. Therefore the TDB (111) surface is not considered in most of the reports in the literature [30,31]. Consequently, to circumvent the dangling bonds inconsistency of the (111) surface as mentioned above, a rough effect of surface reconstruction is taken into consideration.…”

Section: Methodsmentioning

confidence: 99%

Preferred growth direction of III–V nanowires on differently oriented Si substrates

Zeng

Fonseka

et al. 2020

Nanotechnology

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One of the nanowire characteristics is its preferred elongation direction. Here, we investigated the impact of Si substrate crystal orientation on the growth direction of GaAs nanowires. We first studied the selfcatalyzed GaAs nanowire growth on Si (111) and Si (001) substrates. SEM observations show GaAs nanowires on Si (001) are grown along four <111> directions without preference on one or some of them. This non-preferential nanowire growth on Si (001) is morphologically in contrast to the extensively reported vertical <111> preferred GaAs nanowire growth on Si (111) substrates. We propose a model based on the initial condition of an ideal Ga droplet formation on Si substrates and the surface free energy calculation which takes into account the dangling bond surface density for different facets. This model provides further understanding of the different preferences in the growth of GaAs nanowires along selected <111> directions depending on the Si substrate orientation. To verify the prevalence of the model, nanowires were grown on Si (311) substrates. The results are in good agreement with the three-dimensional mapping of surface free energy by our model. This general model can also be applied to predictions of nanowire preferred growth directions by the vapor-liquid-solid growth mode on other group IV and III-V substrates.

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π conjugation in the epitaxial Si(111)- 3×3 surface: Unconventional “bamboo hat” bonding geometry for Si

Cited by 6 publications

References 43 publications

Nontypical Wulff-Shape Silicon Nanosheets with High Catalytic Activity

Nontypical Wulff-Shape Silicon Nanosheets with High Catalytic Activity

Topological band evolution between Lieb and kagome lattices

Preferred growth direction of III–V nanowires on differently oriented Si substrates

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