A5079583428- 2D Materials and Applications
- Graphene research and applications
- Topological Materials and Phenomena
- Quantum and electron transport phenomena
- Terahertz technology and applications
- Perovskite Materials and Applications
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Quantum Chemical Studies
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- MXene and MAX Phase Materials
- Chalcogenide Semiconductor Thin Films
- Mechanical and Optical Resonators
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Organic and Molecular Conductors Research
- Multiferroics and related materials
- Machine Learning in Materials Science
- Quantum Dots Synthesis And Properties
- Magnetic properties of thin films
- Photonic Crystals and Applications
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
Cornell University
2018-2025
Nanjing Normal University
2025
Mayo Clinic in Florida
2019-2024
WinnMed
2019-2024
National Institute for Materials Science
2023
The University of Texas at Austin
2023
Taiyuan University of Technology
2022-2023
Changji University
2023
Shanghai Jiao Tong University
2023
South Central Minzu University
2017-2022
The electronic properties of ultrathin crystals molybdenum disulfide consisting $N=1,2,\dots{},6$ S-Mo-S monolayers have been investigated by optical spectroscopy. Through characterization absorption, photoluminescence, and photoconductivity spectroscopy, we trace the effect quantum confinement on material's structure. With decreasing thickness, indirect band gap, which lies below direct gap in bulk material, shifts upwards energy more than 0.6 eV. This leads to a crossover direct-gap...
Time-resolved, pulsed terahertz spectroscopy has developed into a powerful tool to study charge carrier dynamics in semiconductors and semiconductor structures over the past decades. Covering energy range from few about 100 meV, radiation is sensitive response of quasiparticles, e.g., free carriers, polarons, excitons. The distinct spectral signatures these different quasiparticles THz allow their discrimination characterization using radiation. This frequency region also well suited for...
Exciton binding energy and excited states in monolayers of tungsten diselenide (WSe(2)) are investigated using the combined linear absorption two-photon photoluminescence excitation spectroscopy. The exciton is determined to be 0.37 eV, which about an order magnitude larger than that III-V semiconductor quantum wells renders observable even at room temperature. spectrum with both experimentally one- active distinct from simple two-dimensional (2D) hydrogenic model. This result reveals...
We demonstrate the continuous tuning of electronic structure atomically thin MoS2 on flexible substrates by applying a uniaxial tensile strain. A redshift at rate ~70 meV per percent applied strain for direct gap transitions, and 1.6 times larger indirect have been determined absorption photoluminescence spectroscopy. Our result, in excellent agreement with first principles calculations, demonstrates potential twodimensional crystals applications electronics optoelectronics.
It has been predicted that application of a strong electric field perpendicular to the plane bilayer graphene can induce significant band gap. We have measured optical conductivity with an efficient electrolyte top gate for photon energy range 0.2--0.7 eV. see emergence new transitions as gap opens. A approaching 200 meV is observed when $\ensuremath{\sim}1\text{ }\text{ }\mathrm{V}/\mathrm{nm}$ applied, inducing carrier density about ${10}^{13}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$. The...
Since graphene has no band gap, photoluminescence is not expected from relaxed charge carriers. We have, however, observed significant light emission under excitation by ultrashort (30-fs) laser pulses. Light was found to occur across the visible spectral range (1.7-3.5 eV), with emitted photon energies exceeding that of (1.5 eV). The exhibits a nonlinear dependence on fluence. In two-pulse correlation measurements, dominant relaxation time tens femtoseconds observed. A two-temperature model...
We describe the electromagnetic theory of second-harmonic generation from surface a sphere that is small compared to wavelength light. In leading-order expansion, radiation emitted in nonlocally excited electric dipole and locally quadrupole modes. analyze problem with particular emphasis on experimental aspects, such as pattern, polarization selection rules, determination nonlinear susceptibilities, efficiency, spectral characteristics.
Significant excitonic effects were observed in graphene by measuring its optical conductivity a broad spectral range including the two-dimensional $\ensuremath{\pi}$-band saddle-point singularities electronic structure. The strong electron-hole interactions manifest themselves an asymmetric resonance peaked at 4.62 eV, which is redshifted nearly 600 meV from value predicted ab initio $GW$ calculations for band-to-band transitions. explained within phenomenological model as Fano interference...