A5033551470- 2D Materials and Applications
- Perovskite Materials and Applications
- MXene and MAX Phase Materials
- Quantum Dots Synthesis And Properties
- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Heusler alloys: electronic and magnetic properties
- Acoustic Wave Resonator Technologies
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Graphene research and applications
- Nanocluster Synthesis and Applications
- Adhesion, Friction, and Surface Interactions
- Organic and Molecular Conductors Research
- Metalloenzymes and iron-sulfur proteins
- Organoselenium and organotellurium chemistry
- Advanced Memory and Neural Computing
- Nanoplatforms for cancer theranostics
- Strong Light-Matter Interactions
- Ultrasonics and Acoustic Wave Propagation
- Ferroelectric and Piezoelectric Materials
- Topological Materials and Phenomena
- Machine Learning in Materials Science
Lawrence Berkeley National Laboratory
2023-2025
Laboratoire de Physique et d’Étude des Matériaux
2024
Stanford University
2017-2023
SLAC National Accelerator Laboratory
2022
We report light emission around 1 eV (1240 nm) from heterostructures of MoS_{2} and WSe_{2} transition metal dichalcogenide monolayers. identify its origin in an interlayer exciton (ILX) by wide spectral tunability under out-of-plane electric field. From the static dipole moment state, temperature twist-angle dependence, comparison with electronic structure calculations, we assign this ILX to fundamental between K valleys system. Our findings gain access physics intrinsically incommensurate...
Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. Because such excitons display weak overlap, most studies have examined only the lowest-energy through photoluminescence. We directly measured dielectric response of interlayer which we accessed using their static electric dipole moment. thereby determined an intrinsic radiative lifetime 0.40 nanoseconds for lowest direct-gap exciton in a...
Stacking van der Waals crystals allows for the on-demand creation of a periodic potential landscape to tailor transport quasiparticle excitations. We investigate diffusion photoexcited electron–hole pairs, or excitons, at interface WS2/WSe2 heterostructure over wide range temperatures. observe appearance distinct interlayer excitons parallel and antiparallel stacking track their through spatially temporally resolved photoluminescence spectroscopy from 30 250 K. While measured exciton...
We investigate the valley Hall effect (VHE) in monolayer WSe2 field-effect transistors using optical Kerr rotation measurements at 20 K. While studies of VHE have so far focused on n-doped MoS2, we observe both n- and p-doping regimes. Hole doping enables access to large spin-splitting valence band this material. The probe spatial distribution carrier imbalance induced by VHE. Under current flow, distinct spin-valley polarization along edges transistor channel. From analysis magnitude...
Er 3 + color centers are promising candidates for quantum science and technology due to their long electron nuclear spin coherence times, as well desirable emission wavelength. By selecting host materials with suitable, controllable properties, we introduce new parameters that can be used tailor the Er3+ spectrum. PbTiO3 is a well-studied ferroelectric material known methods of engineering different domain configurations through epitaxial strain. distorting structure Er3+-doped thin films,...
Tip-enhanced photoluminescence (TRPL) is a powerful technique for spatially and spectrally probing local optical properties of 2-dimensional (2D) materials that are modulated by the heterogeneities, revealing inaccessible dark states due to bright state overlap in conventional far-field microscopy at room temperature. While scattering-type near-field probes have shown potential selectively enhance reveal exciton emission, their technical complexity sensitivity can pose challenges under...
van der Waals (vdW) heterostructures provide a powerful method to control the alignment of energy bands atomically thin 2D materials. Under light illumination, optical responses are dominated by Coulomb-bound electron–hole quasiparticles, for example, excitons, trions, and biexcitons, whose contributions accordingly depend on types heterostructures. For type-II heterostructures, it has been well established that excitation results in electrons holes separated different layers, radiative...
Abstract Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a Fermi or TLL have suggested dependence on the underlying substrate, however, unveiling physical details electronic contributions from substrate require cross-correlative investigation. Here, we study formation MTBs defectively engineered WS 2 atop graphene,...
Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a Fermi or TLL have suggested dependence on the underlying substrate, however, unveiling physical details electronic contributions from substrate require cross-correlative investigation. Here, we study formation MTBs defectively engineered WS$_2$ atop graphene, where...
Moiré heterostructures of layered materials such as transition metal dichalcogenides enable periodic arrays localized quasi-particles with long-range Coulomb interactions which can host a plethora quantum phenomena. Depending on the lattice mismatch and twist angle across individual layers, resulting moiré potential modulates distribution electronic states, significantly changing landscape excitons their characteristics. We employ simultaneous hyperspectral electron energy loss spectroscopy...
Interlayer excitons (IXs) in transition metal dichalcogenides are promising for applications opto-electronics and quantum technologies. They have strongly tunable energy through external electric fields can be confined to specific moiré sites, which adjustable twist angles. IX emission exhibits a strong blueshift with optical pumping densities has been correlated exciton-exciton interaction [1]. By directly imaging the time-resolved angle-resolved photoemission spectroscopy (trARPES), we...
Er3+ color centers are promising candidates for quantum science and technology due to their long electron nuclear spin coherence times, as well desirable emission wavelength. By selecting host materials with suitable, controllable properties, we introduce new parameters that can be used tailor the spectrum. PbTiO3 is a well-studied ferroelectric material known methods of engineering different domain configurations through epitaxial strain. distorting structure Er3+-doped thin films,...
Monolayer transition metal dichalcogenide (TMD) materials have exciting potential for applications in spintronics. Due to the monolayer geometry and strong spin-orbit coupling, they are predicted a coupled spin valley Hall effect (SVHE), where valley-polarized conduction carriers opposite [1, 2, 3]. This could provide valley-preserved switching future magnetic memories. WSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is an attractive...
Interlayer excitons (ILXs) - electron-hole pairs bound across two atomically thin layered semiconductors have emerged as attractive platforms to study exciton condensation, single-photon emission and other quantum-information applications. Yet, despite extensive optical spectroscopic investigations, critical information about their size, valley configuration the influence of moiré potential remains unknown. Here, we captured images time- momentum-resolved distribution both electron hole that...
We directly image valley-polarized excitons in a WSe 2 /MoS heterostructure using time- and angle-resolved micro photoemission spectroscopy, before after interlayer exciton formation.