A5079722458- Microstructure and Mechanical Properties of Steels
- Microstructure and mechanical properties
- Plasmonic and Surface Plasmon Research
- Particle Accelerators and Free-Electron Lasers
- Magnetic properties of thin films
- Particle accelerators and beam dynamics
- 2D Materials and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Magnetic Properties and Applications
- Superconducting Materials and Applications
- Photonic and Optical Devices
- Electron and X-Ray Spectroscopy Techniques
- Metal and Thin Film Mechanics
- X-ray Diffraction in Crystallography
- Quantum Dots Synthesis And Properties
- Spectroscopy Techniques in Biomedical and Chemical Research
- Near-Field Optical Microscopy
- Perovskite Materials and Applications
- Metallurgical and Alloy Processes
- Heusler alloys: electronic and magnetic properties
- Strong Light-Matter Interactions
- Metallic Glasses and Amorphous Alloys
- Plant Surface Properties and Treatments
- Advanced Materials and Mechanics
- Advanced X-ray Imaging Techniques
Pohang University of Science and Technology
2008-2024
Ulsan National Institute of Science and Technology
2020-2022
Ferro (United States)
2014
Institute of Science and Technology
2014
Lawrence Berkeley National Laboratory
2003
Pohang Accelerator Laboratory
2001
Research Institute of Industrial Science and Technology
1992-1994
Northwestern University
1987-1989
Abstract The tunability of the bandgap, absorption and emission energies, photoluminescence (PL) quantum yield, exciton transport, energy transfer in transition metal dichalcogenide (TMD) monolayers provides a new class functions for wide range ultrathin photonic devices. Recent strain‐engineering approaches have enabled to tune some these properties, yet dynamic control at nanoscale with real‐time ‐space characterizations remains challenge. Here, nano‐mechanical naturally‐formed wrinkles...
Abstract Emerging photo-induced excitonic processes in transition metal dichalcogenide (TMD) heterobilayers, e.g., interplay of intra- and inter-layer excitons conversion to trions, allow new opportunities for ultrathin hybrid photonic devices. However, with the associated large degree spatial heterogeneity, understanding controlling their complex competing interactions TMD heterobilayers at nanoscale remains a challenge. Here, we present an all-round dynamic control interlayer-excitons...
Abstract Photoluminescence (PL), a photo-excited spontaneous emission process, provides wealth of optical and electronic properties materials, which enable microscopic spectroscopic imaging, biomedical sensing diagnosis, range photonic device applications. However, conventional far-field PL measurements have limitations in sensitivity spatial resolution, especially to investigate single nano-materials or nano-scale dimension them. In contrast, tip-enhanced photoluminescence (TEPL)...
Understanding and controlling the nanoscale transport of excitonic quasiparticles in atomically thin two-dimensional (2D) semiconductors are crucial to produce highly efficient nano-excitonic devices. Here, we present a nanogap device selectively confine excitons or trions 2D transition metal dichalcogenides at nanoscale, facilitated by drift-dominant exciton funneling into strain-induced local spot. We investigate spatiospectral characteristics funneled WSe2 monolayer (ML) converted MoS2 ML...
The generation of high-purity localized trions, dynamic exciton-trion interconversion, and their spatial modulation in two-dimensional (2D) semiconductors are building blocks for the realization trion-based optoelectronic devices. Here, we present a method all-optical control exciton-to-trion conversion process its distributions MoS2 monolayer. We induce nanoscale strain gradient 2D crystal transferred on lateral metal-insulator-metal (MIM) waveguide exploit propagating surface plasmon...
Exciton-polaritons confined in plasmonic cavities are hybridized light-matter quasiparticles, with distinct optical characteristics compared to plasmons and excitons alone. Here, we demonstrate the electric tunability of a single polaritonic quantum dot operating at room temperature electric-field tip-enhanced strong coupling spectroscopy. For nanoplasmonic tip cavity variable dc local field, dynamically control Rabi frequency corresponding polariton emission, crossing weak coupling. We...
When synchrotron radiation is used as an excitation source, the total reflection x-ray fluorescence analysis of surface contamination on silicon wafer has extremely low background intensity that determines minimum detection limit. In this article, spectrum originating from photoelectron bremsstrahlung calculated using Monte Carlo method. The doubly differential electron cross sections obtained Born approximation modified by Elwert factor and with use form approach for screening are instead...
Abstract Spatial manipulation of excitonic quasiparticles, such as neutral excitons, charged and interlayer in two-dimensional semiconductors offers unique capabilities for a broad range optoelectronic applications, encompassing photovoltaics, exciton-integrated circuits, quantum light-emitting systems. Nonetheless, their practical implementation is significantly restricted by the absence electrical controllability short lifetime low exciton funneling efficiency at room temperature, which...
A quantitative single-molecule tip-enhanced Raman spectroscopy (TERS) study at room temperature remained a challenge due to the rapid structural dynamics of molecules exposed air. Here, we demonstrate hyperspectral TERS imaging single or few brilliant cresyl blue (BCB) temperature, along with spectral analyses. Robust chemical is enabled by freeze-frame approach using thin Al2O3 capping layer, which suppresses diffusions and inhibits reactions contamination in For resolved spatially image,...
Strain engineering of perovskite quantum dots (pQDs) enables widely tunable photonic device applications. However, manipulation at the single-emitter level has never been attempted. Here, we present a tip-induced control approach combined with tip-enhanced photoluminescence (TEPL) spectroscopy to engineer strain, bandgap, and emission yield single pQD. Single CsPbBrxI3–x pQDs are clearly resolved through hyperspectral TEPL imaging ∼10 nm spatial resolution. The plasmonic tip then directly...
Optical computing with optical transistors has emerged as a possible solution to the exponentially growing computational workloads, yet an on-chip nano-optical modulation remains challenge due intrinsically noninteracting nature of photons in addition diffraction limit. Here, we present all-optical approach toward nano-excitonic using atomically thin WSe2/Mo0.5W0.5Se2 heterobilayer inside plasmonic tip-based nanocavity. Through wavefront shaping, selectively modulate tip-enhanced...
Formation-energy formalism for a general interface is developed and applied to $\ensuremath{\alpha}\text{-Fe}$ host with boron (B) impurities. In bulk $\ensuremath{\alpha}\text{-Fe}$, B impurities prefer be located at substitutional position rather than interstitial. The estimated formation energy of lower that interstitial by 0.10 eV in the dilute impurity limit. At surface, however, site found preferred, on top surface are most stable as compared those subsurface positions. stability...
Gap plasmon (GP) resonance in static surface-enhanced Raman spectroscopy (SERS) structures is generally too narrow and not tunable. Here, we present an adaptive gap-tunable SERS device to selectively enhance modulate different vibrational modes via active flexible Au nanogaps, with optical control. The tunability of GP up ∼1200 cm–1 by engineering gap width, facilitated mechanical bending a polyethylene terephthalate substrate. We confirm that the tuned enhances spectral regions molecules....