A5007258608- 2D Materials and Applications
- Graphene research and applications
- MXene and MAX Phase Materials
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Thermal Radiation and Cooling Technologies
- Mechanical and Optical Resonators
- Nanowire Synthesis and Applications
- Photonic Crystals and Applications
- Boron and Carbon Nanomaterials Research
- Carbon Nanotubes in Composites
- Photonic and Optical Devices
- Physics of Superconductivity and Magnetism
- Strong Light-Matter Interactions
- Plasmonic and Surface Plasmon Research
- Topological Materials and Phenomena
- ZnO doping and properties
- Chalcogenide Semiconductor Thin Films
- Advanced MEMS and NEMS Technologies
- Quantum Dots Synthesis And Properties
- Quantum and electron transport phenomena
- Advanced Memory and Neural Computing
- Superconducting Materials and Applications
- Magnetic properties of thin films
- Diamond and Carbon-based Materials Research
Kyung Hee University
2017-2024
Korea University
2021
Korea Institute of Science and Technology
2021
Korea Institute of Energy Research
2021
Korea Research Institute of Ships and Ocean Engineering
2021
Institute for Basic Science
2021
Columbia University
2014-2020
Seoul National University
2007-2019
Yonsei University
2019
Sejong University
2019
We have measured circularly polarized photoluminescence in monolayer MoSe2 under perpendicular magnetic fields up to 10 T. At low doping densities, the neutral and charged excitons shift linearly with field strength at a rate of ∓0.12 meV/T for emission arising, respectively, from K K' valleys. The opposite sign different valleys demonstrates lifting valley degeneracy. magnitude Zeeman agrees predicted moments carriers conduction valence bands. relative intensity exciton is modified by...
Emerging two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have been intensively studied because of their novel properties for advanced electronics and optoelectronics. However, 2D materials are by nature sensitive to environmental influences, temperature, humidity, adsorbates, trapped charges in neighboring dielectrics. Therefore, it is crucial develop device architectures that provide both high performance long-term stability. Here we report dual-gated van der Waals...
Monolayer MoS2, among many other transition metal dichalcogenides, holds great promise for future applications in nanoelectronics and optoelectronics due to its ultrathin nature, flexibility, sizable band gap, unique spin-valley coupled physics. However, careful study of these properties at low temperature has been hindered by an inability achieve low-temperature Ohmic contacts monolayer particularly carrier densities. In this work, we report a new contact scheme that utilizes cobalt (Co)...
Large-area "in situ" transition-metal substitution doping for chemical-vapor-deposited semiconducting transition-metal-dichalcogenide monolayers deposited on dielectric substrates is demonstrated. In this approach, the stable and preserves monolayer's nature, along with other attractive characteristics, including direct-bandgap photoluminescence.
Significance The ability to electrically control collective electron states is a central goal of materials research and may allow for the development novel devices. 1T-TaS 2 an ideal candidate such devices due existence various charge ordered in its phase diagram. Although techniques have been demonstrated manipulate order , fundamental understanding effects still lacking, methods used are incompatible with device fabrication. By using both high-resolution transmission microscopy electronic...
Interfacial charge separation and recombination at heterojunctions of monolayer transition metal dichalcogenides (TMDCs) are interest to two-dimensional optoelectronic technologies. These processes can involve large changes in parallel momentum vector due the confinement electrons holes K valleys each layer. Because these high-momentum usually not aligned across interface two TMDC monolayers, how is conserved or process becomes a key question. Here we probe this question using model system...
Since the discovery of ferromagnetic two-dimensional (2D) van der Waals (vdW) crystals, significant interest on such 2D magnets has emerged, inspired by their appealing properties and integration with other family for unique heterostructures. In known magnets, spin-orbit coupling (SOC) stabilizes perpendicular magnetic anisotropy (PMA). Such a strong SOC could also lift chiral degeneracy, leading to formation topological textures as skyrmions through Dzyaloshinskii-Moriya interaction (DMI)....
A fundamental understanding of chemical sensing mechanisms in graphene-based field-effect transistors (chemFETs) is essential for the development next generation sensors. Here we explore hidden modalities responsible tailoring gas detection ability pristine graphene sensors by exposing chemFETs to electron donor and acceptor trace vapors. We uncover that sensitivity (in terms modulation electrical conductivity) not necessarily intrinsic graphene, but rather it facilitated external defects...
Ultrafast electrically driven nanoscale light sources are critical components in nanophotonics. Compound semiconductor-based for the nanophotonic platforms have been extensively investigated over past decades. However, monolithic ultrafast with a small footprint remain challenge. Here, we demonstrate graphene emitters that achieve pulse generation up to 10 GHz bandwidth across broad spectral range from visible near-infrared. The fast response results charge-carrier dynamics and weak...
Monolayers of transition-metal dichalcogenides such as WSe2 have become increasingly attractive due to their potential in electrical and optical applications. Because the properties these 2D systems are known be affected by surroundings, we report how choice substrate material affects monolayer WSe2. To accomplish this study, pump-density-dependent micro-photoluminescence measurements performed with time-integrating time-resolving acquisition techniques. Spectral information power-dependent...
Controlling thermal radiation is central in a range of applications including sensing, energy harvesting, and lighting. The emission spectrum can be strongly modified through the electromagnetic local density states (EM LDOS) nanoscale-patterned metals semiconductors. However, these materials become unstable at high temperature, preventing improvements radiative efficiency such as thermophotovoltaics. Here, we report stable high-temperature based on hot electrons (>2000 K) graphene coupled...
Efficient doping for modulating electrical properties of two-dimensional (2D) transition metal dichalcogenide (TMDC) semiconductors is essential meeting the versatile requirements future electronic and optoelectronic devices. Because semiconductors, including TMDCs, typically involves generation charged dopants that hinder charge transport, tackling Coulomb scattering induced by externally introduced remains a key challenge in achieving ultrahigh mobility 2D semiconductor systems. In this...
A single-layer graphene is synthesized on Cu foil in the absence of H2 flow by plasma enhanced chemical vapor deposition (PECVD). In lieu an explicit flow, hydrogen species are produced during methane decomposition process into their active (CHx<4), assisted with plasma. Notably, early stage growth depends strongly power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when power higher than 120 because partial pressures effectively tuned...
With its electrical carrier type as well densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light–graphene interactions, indirect effects arising from induced charge traps underneath photoactive light–substrate interactions must be better understood and harnessed. Here, we study local doping effect in using focused-laser irradiation, which governs trapping ejecting behavior of trap sites gate oxide. The...
An ambipolar dual-channel field-effect transistor (FET) with a WSe2 /MoS2 heterostructure formed by separately controlled individual channel layers is demonstrated. The FET shows switchable behavior independent carrier transport of electrons and holes in the MoS2 , respectively. Moreover, photoresponse studied at heterointerface FET.
We investigate the voltage control of magnetism in a van der Waals (vdW) heterostructure device consisting two distinct vdW materials, ferromagnetic Fe3-xGeTe2 and ferroelectric In2Se3. It is observed that gate voltages applied to Fe3-xGeTe2/In2Se3 modulate magnetic properties with significant decrease coercive field for both positive negative voltages. Raman spectroscopy on shows voltage-dependent increase in-plane In2Se3 lattice constants polarities. Thus, field, regardless polarity, can...
This study addresses high electric field transport in multilayer black phosphorus (BP) effect transistors with self‐heating and thermal spreading by dielectric engineering. Interestingly, a BP device on SiO 2 substrate exhibits maximum current density of 3.3 × 10 A m −2 at an 5.58 MV −1 , several times higher than MoS . The breakdown thermometry analysis reveals that is impeded along the BP–dielectric interface, resulting plateau inside channel eventual Joule breakdown. Using size‐dependent...
Transition metal dichalcogenides (TMDs) have emerged as promising materials to complement graphene for advanced optoelectronics. However, irreversible degradation of chemical vapor deposition-grown monolayer TMDs via oxidation under ambient conditions limits applications TMD-based devices. Here, the growth oxidation-resistant tungsten disulfide (WS2 ) monolayers on is demonstrated, and mechanism WS2 SiO2 , graphene/SiO2 suspended in air elucidated. While a substrate begins within weeks,...