A5003315529- Graphene research and applications
- 2D Materials and Applications
- Topological Materials and Phenomena
- Quantum and electron transport phenomena
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- MXene and MAX Phase Materials
- Semiconductor materials and devices
- Diamond and Carbon-based Materials Research
- Surface and Thin Film Phenomena
- Ga2O3 and related materials
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Condensed Matter Physics
- Metal and Thin Film Mechanics
- Medical and Health Sciences Research
- Perovskite Materials and Applications
- Gas Sensing Nanomaterials and Sensors
- Quantum Dots Synthesis And Properties
- Physics of Superconductivity and Magnetism
- Nanowire Synthesis and Applications
- Graphene and Nanomaterials Applications
- Boron and Carbon Nanomaterials Research
- Magnetic properties of thin films
- Advanced X-ray Imaging Techniques
Lawrence Berkeley National Laboratory
2016-2024
National Institute for Materials Science
2021
KTH Royal Institute of Technology
2021
Stockholm University
2021
United States Naval Research Laboratory
2021
Carnegie Mellon University
2021
Technical University of Denmark
2021
Aarhus University
2021
GasPorOx (Sweden)
2020
Advanced Light Source
2018
Structural defects in 2D materials offer an effective way to engineer new material functionalities beyond conventional doping semiconductors. Specifically, deep in-gap defect states of chalcogen vacancies have been associated with intriguing phenomena monolayer transition metal dichalcogenides (TMDs). Here, we report the direct experimental correlation atomic and electronic structure a sulfur vacancy WS2 by combination CO-tip noncontact force microscopy (nc-AFM) scanning tunneling (STM)....
The layered van der Waals antiferromagnet MnBi${}_{2}$Te${}_{4}$ has been predicted previously to realize the first intrinsic magnetic topological insulator. Here, authors report spin- and angle-resolved photoemission experiments for MnBi${}_{2}$Te${}_{4}$(0001) surface, revealing a surface state in bulk band gap providing evidence interplay between exchange interaction spin-orbit coupling electronic structure. thus constitutes promising candidate exploit of states order spintronic device concepts.
The doping of graphene to tune its electronic properties is essential for further use in carbon-based electronics. Adapting strategies from classical silicon-based semiconductor technology, we the incorporation heteroatoms 2D network as a straightforward way achieve this goal. Here, report on synthesis boron-doped Ni(111) chemical vapor deposition process triethylborane one hand and by segregation boron bulk substrate crystal other hand. environment was determined x-ray photoelectron...
Control of impurity concentrations in semiconducting materials is essential to device technology. Because their intrinsic confinement, the properties two-dimensional semiconductors such as transition metal dichalcogenides (TMDs) are more sensitive defects than traditional bulk materials. The technological adoption TMDs dependent on mitigation deleterious and guided incorporation functional foreign atoms. first step toward control identification assessment electronic properties. Here, we...
The doping of quasi-freestanding graphene (QFG) on H-terminated, Si-face 6H-, 4H-, and 3C-SiC is studied by angle-resolved photoelectron spectroscopy close to the Dirac point. Using semi-insulating as well n-type doped substrates we shed light contributions charge carrier density in QFG caused (i) spontaneous polarization substrate, (ii) band alignment between substrate layer. In this way provide quantitative support for previously suggested model SiC (Ristein et al 2012 Phys. Rev. Lett. 108 246104).
We investigate the effects of environmental dielectric screening on electronic dispersion and band gap in atomically-thin, quasi two-dimensional (2D) semiconductor WS$_2$ using correlative angle-resolved photoemission optical spectroscopies, along with first-principles calculations. find main effect increased to be a reduction gap, little change structure. These essentially rigid shifts bands results from special spatial structure changes Coulomb potential induced by environment 2D limit....
Abstract Harnessing electronic excitations involving coherent coupling to bosonic modes is essential for the design and control of emergent phenomena in quantum materials. In situations where charge carriers induce a lattice distortion due electron-phonon interaction, conducting states get “dressed", which leads formation polaronic quasiparticles. The exploration effects on low-energy its infancy two-dimensional Here, we present discovery an interlayer plasmon polaron heterostructures...
We report on strong coupling of the charge carrier plasmon $\omega_{PL}$ in graphene with surface optical phonon $\omega_{SO}$ underlying SiC(0001) substrate low electron concentration ($n=1.2\times 10^{15}$ $cm^{-3}$) long wavelength limit ($q_\parallel \rightarrow 0$). Energy dependent energy-loss spectra give for first time clear evidence two coupled phonon-plasmon modes $\omega_\pm$ separated by a gap between 0$) and $\omega_{TO}$ >> 0$), transverse mode, Fano-type shape, particular...
Large hexagonal single-crystalline domains of single-layer graphene are epitaxially grown by ambient-pressure chemical vapor deposition over a thin Cu(111) film deposited on c-plane sapphire. The with maximum size 100 µm oriented in the same direction due to epitaxial growth. Reflecting high crystallinity, clear band structure Dirac cone is observed angle-resolved photoelectron spectroscopy (ARPES), and carrier mobility exceeding 4,000 cm2 V-1 s-1 obtained SiO2/Si at room temperature. Our...
We report on experimental and theoretical investigations of nitrogen-doped graphene. The incorporation nitrogen was achieved during chemical-vapor deposition Ni(111) using pyridine as a precursor. obtained graphene layers were investigated photoelectron spectroscopy. By studying C $1s$ N core levels, we show that the content is influenced by growth temperature determine atomic arrangement atoms. Valence-band spectra leads to broadening photoemission lines shift $\ensuremath{\pi}$ band....
Two-dimensional materials with engineered composition and structure will provide designer beyond conventional semiconductors. However, the potentials of defect engineering remain largely untapped, because it hinges on a precise understanding electronic excitonic properties, which are not yet predictable by theory alone. Here, we utilize correlative, nanoscale photoemission spectroscopy to visualize how local introduction defects modifies properties two-dimensional at nanoscale. As model...
Bilayer graphene was theorized to host a moire miniband with flat dispersion if the layers are stacked at specific twist angles known as magic angles. Recently, such twisted bilayer (tBLG) first angle reported exhibit correlated insulating state and superconductivity, where presence of in system is thought be essential for emergence these ordered phases transport measurements. Tunneling spectroscopy electronic compressibility measurements tBLG have revealed van Hove singularity that...
Author(s): Kastl, C; Chen, CT; Koch, RJ; Schuler, B; Kuykendall, TR; Bostwick, A; Jozwiak, Seyller, T; Rotenberg, E; Weber-Bargioni, Aloni, S; Schwartzberg, AM | Abstract: Van der Waals epitaxy enables the integration of 2D transition metal dichalcogenides with other layered materials to form heterostructures atomically sharp interfaces. However, ability fully utilize and understand these using surface science techniques such as angle resolved photoemission spectroscopy (ARPES) scanning...
The discovery of new families exfoliatable 2D crystals that have diverse sets electronic, optical, and spin-orbit coupling properties enables the realization unique physical phenomena in these few-atom-thick building blocks proximity to other materials. Herein, using NaSn2As2 as a model system, we demonstrate layered Zintl phases having stoichiometry ATt2Pn2 (A = group 1 or 2 element, Tt 14 tetrel Pn 15 pnictogen element) feature networks separated by van der Waals gaps can be readily...
Focusing soft X-ray beams to small spots enables many powerful analysis techniques for spot and/or imaging. At the MAESTRO beamline [1], located at Advanced Light Source in...
The search for materials with flat electronic bands continues due to their potential drive strong correlation and symmetry breaking orders. Electronic moirés formed in van der Waals heterostructures have proved be an ideal platform. However, there is no holistic experimental picture how superlattices modify structure. By combining spatially resolved angle-resolved photoemission spectroscopy optical spectroscopy, we report the first direct evidence of strongly correlated phases evolve from a...
Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many these are limited by complex interactions between carbon-based metals. In this work, we experimentally investigate structural transition metals palladium (Pd) titanium (Ti), which been confirmed density functional simulations. We find that adsorption on is more energetically favorable...
There is a substantial interest in the heterostructures of semiconducting transition metal dichalcogenides (TMDCs) amongst each other or with arbitrary materials, through which control chemical, structural, electronic, spintronic, and optical properties can lead to change device paradigms. A critical need understand interface between TMDCs insulating substrates, for example high-$\kappa$ dielectrics, strongly impact electronic such as gap. Here we show that chemical single-layer (SL) TMDC,...
The efficiency and stability of ${\mathrm{RuO}}_{2}$ in electrocatalysis has made this material a subject intense fundamental industrial interest. surface functionality is rooted its electronic magnetic properties, determined by complex interplay lattice-, spin-rotational, time-reversal symmetries, as well the competition between Coulomb kinetic energies. This was predicted to produce network Dirac nodal lines (DNLs), where valence conduction bands touch along continuous momentum space. Here...
Using inelastic electron scattering in combination with dielectric theory simulations on differently prepared graphene layers silicon carbide, we demonstrate that the coupling between 2D plasmon of and surface optical phonon substrate cannot be quenched by modification interface via intercalation. The intercalation rather provides additional modes like, e.g., silicon-hydrogen stretch mode case hydrogen or silicon-oxygen vibrations for water couple to plasmons graphene. Furthermore, bilayer...