Optical properties of silicene, Si/Ag(111), and Si/Ag(110)

Hogan, Conor; Pulci, Olivia; Gori, Paola; Bechstedt, F.; Martin, D. S.; Barritt, E. E.; Curcella, Alberto; Prévot, Geoffroy; Borensztein, Y.

doi:10.1103/physrevb.97.195407

Cited by 38 publications

(41 citation statements)

References 64 publications

(91 reference statements)

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“…The solution of the Bethe-Salpeter equation on top of DFT-GW is the state-of-the-art first principles approach to calculate neutral excitations in solid-state systems [1], with successful applications to, molecules [55,72], surfaces [73,74], two-dimensional materials [75,76], and nanostructures [77,78], including biomolecules in complex environments [79,80]. The BSE is a Dyson equation for the four point response function L. It can be rewritten as an eigenproblem for a two-particle effective Hamiltonian H 2p in the basis of electron and hole pairs |eh .…”

Section: Optical Absorptionmentioning

confidence: 99%

Many-body perturbation theory calculations using the yambo code

Sangalli

Ferretti

Miranda

et al. 2019

J. Phys.: Condens. Matter

403

349

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yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independentparticle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oft-neglected physical effects such as electron-phonon interactions to the implementation of a real-time propagation scheme for simulating linear and nonlinear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools. CONTENTS

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Section: Optical Absorptionmentioning

confidence: 99%

Many-body perturbation theory calculations using the yambo code

Sangalli

Ferretti

Miranda

et al. 2019

J. Phys.: Condens. Matter

403

349

View full text Add to dashboard Cite

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“…45 The local density approximation (LDA) was used as in previous successful studies on Si/Ag(110) and Si/Ag(111). 31,46,47 The kinetic energy cutoff was 30 Ry. The theoretical Ag lattice constant of 4.075 Å was used (experiment: 4.085 Å).…”

Section: Gixdmentioning

confidence: 99%

Demonstration of the Existence of Dumbbell Silicene: A Stable Two-Dimensional Allotrope of Silicon

et al. 2021

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We report a combined experimental and theoretical study on the formation of dumbbell silicene structures on Ag(110). High-resolution scanning tunneling microscopy (STM) reveals a rich tapestry of adatom-free and -decorated bidimensional silicene phases covering the whole Ag(110) surface. The most thermodynamically stable silicene models obtained from densityfunctional theory (DFT) perfectly reproduce all features observed by STM. These phases correspond to different Si buckled honeycomb reconstructions ((13´4), c(18´4) and c(8´4)) composed of two periodic motifs common to all structural models. DFT calculations show that these reconstructions are stabilized by the presence of ordered arrays of Si adatoms adsorbed on top of silicene in a dumbbell configuration. Grazing incidence X-ray diffraction (GIXD) measurements confirm the growth of a dumbbell silicene layer. The structure factor values are well reproduced by a (13´4) model with 4 Si adatoms per unit cell and a slight distortion of the hexagonal unit cell. Our STM-DFT-GIXD study demonstrates the formation of dumbbell silicene, a theoretically predicted two-dimensional Si allotrope. This opens up perspectives for tuning the peculiar properties of silicene.

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“…34,35 However, rapidly various controversies have emerged about the origin of the various surface reconstructions observed, including (4×4), (√13×√13)R13.9°, (√7×√7)R19.1° and (2√3×2√3)R30° with respect to Ag(111). 23,[36][37][38] First-principles calculations demonstrated that the linear dispersion band observed by ARPES experiments could originate from the hybridization states between silicene and Ag(111) surface. 39 Besides, its impressive stability was definitely ascribed to covalent bonds with the substrate.…”

Section: Introductionmentioning

confidence: 99%

Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC

et al. 2022

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Graphene, consisting of an inert, thermally stable material with an atomically flat, dangling bond-free surface is by essence an ideal template layer for van der Waals heteroepitaxy of two-dimensional materials such as silicene. However, depending on the synthesis method and growth parameters, graphene (Gr) substrates could exhibit, on a single sample, various surface structures, thicknesses, defects, and step heights. These structures noticeably affect the growth mode of epitaxial layers, e.g. turning the layer-by-layer growth into the Volmer Weber growth promoted by defect-assisted nucleation. In this work, the growth of silicon on chemical vapor deposited epitaxial Gr (1 ML Gr/1ML Gr buffer) on 6H-SiC(0001) substrate is investigated by a combination of atomic force microscopy (AFM), scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy measurements. It is shown that the perfect control of full-scale almost defect-free 1 ML Gr with a single surface structure and the ultra-clean conditions for molecular beam epitaxy (MBE) deposition of silicon represent key prerequisites for ensuring the growth of extended silicene sheets on epitaxial graphene. At low coverages, the deposition of Si produces large silicene sheets (some hundreds of nanometers large) attested by both AFM and SEM observations and the onset of a Raman peak at 560 cm -1 very close to the theoretical value of 570 cm -1 calculated for freestanding silicene. This vibrational mode at 560 cm -1 represents the highest ever experimentally measured value and is representative of quasi-free standing silicene with almost no interaction with inert non-metal substrates.From a coverage rate of 1ML, the silicene sheets disappear at the expense of 3D Si dendritic islands whose density, size, and thickness increase with the deposited thickness. From this coverage, the Raman mode assigned to quasi-free standing silicene totally vanishes, and the 2D flakes of silicene are no longer observed by AFM. The experimental results are in very good agreement with the results of kinetic Monte-Carlo simulations that rationalize the initial flake growth in solid-state dewetting conditions, followed by the growth of ridges surrounding and covering the 2D flakes. A full description of the growth mechanism is given. This study, which covers a wide range of growth parameters, challenges recent results stating the impossibility to grow silicene on a carbon inert surface and is very promising for large scale silicene growth. It definitely shows that silicene growth can be achieved using perfectly controlled and ultra-clean deposition conditions and an almost defect-free Gr substrate.

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Optical properties of silicene, Si/Ag(111), and Si/Ag(110)

Cited by 38 publications

References 64 publications

Many-body perturbation theory calculations using the yambo code

Many-body perturbation theory calculations using the yambo code

Demonstration of the Existence of Dumbbell Silicene: A Stable Two-Dimensional Allotrope of Silicon

Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC

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