A5057660345- Graphene research and applications
- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- 2D Materials and Applications
- Boron and Carbon Nanomaterials Research
- MXene and MAX Phase Materials
- Diamond and Carbon-based Materials Research
- Topological Materials and Phenomena
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Advancements in Battery Materials
- Semiconductor Quantum Structures and Devices
- Ancient and Medieval Archaeology Studies
- Graphite, nuclear technology, radiation studies
- Spectroscopy and Quantum Chemical Studies
- Gold and Silver Nanoparticles Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Supercapacitor Materials and Fabrication
- Graphene and Nanomaterials Applications
- Nuclear reactor physics and engineering
- Real-Time Systems Scheduling
- Advanced Chemical Sensor Technologies
- Engine and Fuel Emissions
- Analytical Chemistry and Chromatography
- Advancements in Semiconductor Devices and Circuit Design
Institute of Physics
2015-2024
University of Duisburg-Essen
2017-2023
University of Rijeka
2023
University of Twente
2021
Iowa State University
2021
Physikalisch-Technische Bundesanstalt
2021
University of Sarajevo
2020
IBM Research - Thomas J. Watson Research Center
1992-1998
IBM (United States)
1993
In this study, we show a direct correlation between the applied mechanical strain and an increase in monolayer MoS2 photoresponsivity. This shows that tensile can improve efficiency of photodetectors. The observed high photocurrent extended response time our devices are indicative predominantly governed by photogating mechanisms, which become more prominent with strain. Furthermore, have demonstrated nonencapsulated be used strain-based for many cycles extensive periods time, showing...
Angle resolved photoelectron spectroscopy (ARPES) is extensively used to characterize the dependence of electronic structure graphene on Ir(111) preparation process. ARPES findings reveal that temperature programmed growth alone or in combination with chemical vapor deposition leads displaying sharp bands. The photoemission intensity Dirac cone monitored as a function increasing area. Electronic features moir\'e superstructure present system, namely minigaps and replica bands are examined...
The ease by which graphene is affected through contact with other materials one of its unique features and defines an integral part potential for applications. Here, it will be demonstrated that intercalation, the insertion atomic layers in between backside supporting substrate, efficient tool to change interaction environment on frontside. By partial intercalation Ir(111) Eu or Cs we induce strongly n-doped patches these intercalants. They coexist nonintercalated, slightly p-doped patches....
The intercalation of Eu underneath Gr on Ir(111) is comprehensively investigated by microscopic, magnetic, and spectroscopic measurements, as well density functional theory. Depending the coverage, intercalated atoms form either a $(2\ifmmode\times\else\texttimes\fi{}2)$ or $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R{30}^{\ensuremath{\circ}}$ superstructure with respect to Gr. We investigate mechanisms penetration through nominally closed sheet measure electronic structures...
Like other 2D materials, the boron-based borophene exhibits interesting structural and electronic properties. While is typically prepared by molecular beam epitaxy, we report here on an alternative way of synthesizing large single-phase domains segregation-enhanced epitaxy. X-ray photoelectron spectroscopy shows that borazine dosing at 1100 °C onto Ir(111) yields a boron-rich surface without traces nitrogen. At high temperatures, thermally decomposes, nitrogen desorbs, boron diffuses into...
Abstract Artificial 2D van der Waals heterostructures with controllable vertical stacking and rotational orientation exhibit multifaceted electronic properties that are appealing for applications in fields ranging from optoelectronics to energy storage. Along transition metal dichalcogenides graphene, borophene has recently emerged as a promising building block devices due its conductive nature well exceptional mechanical properties. Here, it is demonstrated the combination of...
Through intercalation of metals and gases the Dirac cone graphene on Ir(111) can be shifted with respect to Fermi level without becoming destroyed by strong hybridization. Here, we use x-ray photoelectron spectroscopy measure C 1s core shift (CLS) in contact a number structurally well-defined layers (O, H, Eu, Cs). By analysis our own additional literature data for decoupled graphene, CLS is found non-monotonic function doping level. For small levels shifts are well described rigid band...
We report the use of time- and angle-resolved two-photon photoemission to map bound, unoccupied electronic structure weakly coupled graphene/Ir(111) system. The energy, dispersion, lifetime lowest three image-potential states are measured. In addition, weak interaction between Ir graphene permits observation resonant transitions from an unquenched Shockley-type surface state substrate graphene/Ir states. image-potential-state lifetimes comparable those mid-gap clean metal surfaces. Evidence...
A major challenge in the investigation of all 2D materials is development synthesis protocols and tools which would enable their large-scale production effective manipulation. The same holds for borophene, where experiments are still largely limited to situ characterizations small-area samples. In contrast, our work based on millimeter-sized borophene sheets, synthesized an Ir(111) surface ultrahigh vacuum. Besides high-quality macroscopic synthesis, as confirmed by low-energy electron...
We observe spatial confinement of Dirac states on epitaxial graphene quantum dots with low-temperature scanning tunneling microscopy after using oxygen as an intercalant to suppress the surface state Ir(111) and effectively decouple from its metal substrate. analyze confined electronic a relativistic particle-in-a-box model find linear dispersion relation. The oxygen-intercalated is $p$ doped [${E}_{\mathrm{D}}=\left(0.64\ifmmode\pm\else\textpm\fi{}0.07\right)$ eV] has Fermi velocity close...
Growth of 2D materials under ultrahigh-vacuum (UHV) conditions allows for an in situ characterization samples with direct spectroscopic insight. Heteroepitaxy transition-metal dichalcogenides (TMDs) UHV remains a challenge integration several different monolayers into new functional systems. In this work, we epitaxially grow lateral WS2-MoS2 and vertical WS2/MoS2 heterostructures on graphene. By means scanning tunneling spectroscopy (STS), first examined the electronic structure monolayer...
It is common knowledge that even a trace amount of chemisorbed species can strongly perturb the surface electronic structure, in particular states, to point their complete eradication. We have confirmed this behavior by adsorbing Li on Ir(111), but surprisingly, we discovered presence graphene does not suppress Ir state. By combining results low-energy electron diffraction and angle-resolved photoemission spectroscopy with density functional theory for modeling studied systems provide...
We present direct experimental evidence of broken chirality in graphene by analyzing electron scattering processes at energies ranging from the linear (Dirac-like) to strongly trigonally warped region. Furthermore, we are able measure energy van Hove singularity $M$ point conduction band. Our data show a very good agreement with theoretical calculations for free-standing graphene. identify new intravalley channel activated case constant contour, which is not suppressed chirality. Finally,...
The CVD growth of bielemental 2D-materials by using molecular precursors involves complex formation kinetics taking place at the surface and sometimes also subsurface regions substrate. Competing microscopic processes fundamentally limit parameter space for optimal desired material. Kinetic limitations diffusion nucleation cause a high density small domains grain boundaries. These are usually overcome increasing temperature decreasing rate. In contrast, nature with limited thermal stability...
We prepared monolayers of tantalum sulfide on Au(111) by evaporation Ta in a reactive background H2S. Under sulfur-rich conditions, 2H-TaS2 formed, whereas under sulfur-poor conditions TaS2–x with 0 ≤ x 1 were found. identified this phase as TaS, structure that can be derived from removal the bottom S layer.
Epitaxial hexagonal boron nitride on Ir(111) is significantly modified by adsorption and intercalation of alkali-metal atoms. Regarding geometry, lifts the two-dimensional layer from its substrate reduces characteristic corrugation imprinted direct contact with metal substrate. Moreover, presence charged species in close proximity to (hBN) strongly shifts electronic structure (valence bands core levels). We used scanning tunneling microscopy, low-energy electron diffraction, x-ray...
Upon adsorption onto epitaxial graphene on Ir(111) at room temperature, Cs adatoms donate part of their charge to the substrate, which effectively creates mutually repelling entities that can diffuse across surface. By using scanning tunneling microscopy 6 K, an ordered hexagonal structure with several rotated domains has been identified. The amount transferred determined from presented valence-band photoemission data. Density-functional calculations show repulsive interaction is...
We present a study of sulfur adsorption on bare Ir(111). Two well-defined superstructures are found: (3×3)R30°and c(4 × 2) S-adlayer. Moreover, we also investigate intercalation graphene For adsorption, is provided either in the form precursor molecule H2S or as elemental through sublimation from FeS2 heated Knudsen cell. On basis scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED), well density functional theory calculations (DFT), model for superstructure...
Exploring the quantum effects in plasmonic responses has attracted growing interest during past decade. Extreme downsizing of nanoparticles and interparticle gaps is promising for altering nature resonances through spillover tunneling electronic wave functions at metallic nanocomposites. While such have been studied frequency domain past, their manifestation ultrafast time remains to be elucidated. In this work, we demonstrate that effect significantly alters response by studying a novel...
Using an unique combination of time and spatially resolved all optical photoluminescence measurement techniques, we have studied the properties intrinsic excitons localized in quantum interface potentials symmetric GaAs/Al0.3Ga0.7As double heterostructures. We find transport these to be extremely sensitive time-dependent, varying conduction, valence band near heterointerface. The observed dynamics been modeled, relying heavily on our previous kinetic results, which proved conclusively that...
Large, high-quality layers of hexagonal boron nitride (hBN) are a prerequisite for further advancement in scientific investigation and technological utilization this exceptional 2D material. Here we address demand by investigating chemical vapor deposition synthesis hBN on an Ir(111) substrate, focus the substrate morphology, more specifically mono-atomic steps that always present all catalytic surfaces practical use. From low-energy electron microscopy atomic force data, able to set up...