A5074749328- Terahertz technology and applications
- Perovskite Materials and Applications
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Semiconductor Quantum Structures and Devices
- Solid-state spectroscopy and crystallography
- Plasmonic and Surface Plasmon Research
- Superconducting and THz Device Technology
- Conducting polymers and applications
- Mechanical and Optical Resonators
- Chalcogenide Semiconductor Thin Films
- Graphene research and applications
- Photonic Crystals and Applications
- Carbon Nanotubes in Composites
- Organic Electronics and Photovoltaics
- Topological Materials and Phenomena
- Acoustic Wave Resonator Technologies
- Silicon Nanostructures and Photoluminescence
- Quantum and electron transport phenomena
- Advanced Thermoelectric Materials and Devices
- Phase-change materials and chalcogenides
- Microwave Engineering and Waveguides
- Metamaterials and Metasurfaces Applications
- Advanced Chemical Sensor Technologies
- Electromagnetic Fields and Biological Effects
Korea Research Institute of Bioscience and Biotechnology
2020-2024
Yonsei University Health System
2020-2024
Yonsei University
2009-2024
Gwangju Institute of Science and Technology
2015-2023
Korea Photonics Technology Institute
2015-2019
Korea Food Research Institute
2014
Chung-Ang University
2014
University of Seoul
2004-2012
Korea Institute of Science and Technology
2009
Rutgers, The State University of New Jersey
2009
We present terahertz spectroscopic measurements of Dirac fermion dynamics from a large-scale graphene that was grown by chemical vapor deposition and on which carrier density modulated electrostatic doping. The measured frequency-dependent optical sheet conductivity shows electron-density-dependence characteristics, can be understood simple Drude model. In low regime, the is constant regardless applied gate voltage, but in high it has nonlinear behavior with respect to voltage. Chemical...
This paper demonstrates the principle of nanoparticle-contrast-agent-enabled terahertz imaging (CATHI) technique, which yields a dramatic sensitivity differential signal from cancer cells with nanoparticles. The (THz) reflection increased beam by 20% in nanoparticles gold nano-rods (GNRs) upon their irradiation infrared (IR) laser, due to temperature rise water surface plasma ploritons. In mode, THz GNRs was 30 times higher than that without GNRs. As high is achieved plasmon resonance...
The absorption and dispersion of aligned single-walled carbon-nanotube films were measured from 0.2 to 2.0 THz using a source freely propagating subpicosecond pulses electromagnetic radiation. real conductivity increased rapidly with increasing frequency up 0.45 decreased at high-frequency range. Maxwell–Garnett model, where the nanotubes embedded in dielectric host, fit results this study Drude–Lorentz model for nanotube network. We have observed transverse phonon mode 2.4 along c...
We demonstrate a highly sensitive THz molecular imaging (TMI) technique involving differential modulation of surface plasmons induced on nanoparticles and obtain target specific in vivo images cancers. This can detect quantities gold as small 15 µM vivo. A comparison TMI with near infrared absorption shows the superior sensitivity TMI. Furthermore, quantification property is excellent, being linearly proportional to concentration nanoparticles. The specificity issue also addressed at ex cell...
Understanding the defect structure in organic-inorganic hybrid perovskite material (OHP) is a crucial role to explain several physical properties such as stability, energy band, carrier mobility, and so on. In solar-cell applications using OHP, finding, understanding, controlling defects essential making more advanced device with high efficiency stability. Naturally, we need find, understand, control possible OHP. However, research field OHP just beginning now. this short review, will...
Over the past two decades, organic–inorganic hybrid perovskite materials (OHP) have been extensively explored across various scientific disciplines, including physics, chemistry, and science, with a primary focus on solar cells. Building numerous studies, development of OHP‐based cells has transitioned into practical product realization, instilling anticipation novel cell advancements. Notably, OHP demonstrates versatility beyond its conventional application in materials. The physical...
Gastric cancer (GC) is recognized as the fifth most prevalent malignant tumor worldwide. It characterized by diverse clinical symptoms, treatment responses, and prognoses. In GC prognosis, promotion of epithelial-mesenchymal transition (EMT) fosters cell invasion metastasis, thereby triggering dissemination cells. This study proposes a nucleic acid amplification circuit-based hydrogel (NACH) assay for identifying exosomal miRNA derived from metastatic GC. The NACH employs rolling circle...
The electrical and optical properties of double-walled carbon nanotubes (DWNTs) have been characterized compared with those single-walled (SWNTs) utilizing terahertz time-domain spectroscopy. power absorption the complex refractive indices DWNTs are smaller than SWNTs. conductivity was also observed to be smaller. experimental results fitted Bruggman effective medium approximations, which has yielded transport parameters such as plasma frequency, damping rate, etc.
This study characterized hydrogen-functionalized carbon nanotube films and compared their characteristics before after they were hydrogen functionalized, using terahertz (THz) time-domain spectroscopy. Reduction of the power absorption samples was observed with functionalization. To analyze experimental results, effective medium approximation (EMA) adopted. Through EMA, plasma frequencies, damping rates, other physical parameters located in THz region determined. In this way, decreases...
Abstract The valid strong THz absorption at 1.58 was probed in the organic-inorganic hybrid perovskite thin film, CH 3 NH PbI , fabricated by sequential vacuum evaporation method. In usual solution-based methods such as 2-step solution and antisolvent, we observed relatively weak two main peaks 0.95 1.87 THz. measured spectrum is analyzed density-functional theory calculations. modes are assigned to Pb-I vibrations of inorganic components tetragonal phase. By contrast, origin due structural...
Terahertz (THz) waves are electromagnetic in the 0.1 to 10 THz frequency range, and imaging is utilized a range of applications, including security inspections, biomedical fields, non-destructive examination materials. However, images have low resolution due long wavelength waves. Therefore, improving current hot research topic. We propose novel network architecture called J-Net, which an improved version U-Net, achieve image super-resolution. It employs simple baseline blocks can extract...
We have investigated the complex conductivity of silver nanowire thin films using terahertz time-domain spectroscopy. Maxwell-Garnett effective medium theory, which accounts for nanowires, is presented in detail theoretically and experimentally. The nanowires exhibits a characteristic non-Drude response applied field polarized longitudinal direction. responses are explained by Gans approximation Drude-Smith model, both agree well with experimental data. Our results provide basis further...
We employed terahertz (THz) spectroscopy to study the optical/electrical properties of various nanocrystal (NC)−carbon nanotube (i.e., single-, double-, and multiwalled) −graphene oxide (GO) hybrid nanostructures. The power absorption conductivity decrease following order single-walled (SWNT) > double-walled (DWNT) multiwalled carbon nanotubes (MWNT) ≈ GO showed a strong dependence on crystallinity graphitic layers. deposition platinum (Pt), copper sulfide (Cu2S), tin (SnO2) NC reduced...
Abstract The exploration of new physical properties for various THz-based applications, such as THz-wave sensing, modulation, and imaging devices, is a key challenge in the research on organic–inorganic hybrid perovskite materials. These applications require satisfactory, sensitive, stable absorption with values between 0.5 3 THz. To achieve these properties, candidate materials should possess purified structure that induces regular fixed phonon modes without any defects or impurities. CH NH...
Owing to their remarkable spin–charge conversion (SCC) efficiency, topological insulators (TIs) are the most attractive candidates for spin–orbit torque generators. The simple method of enhancing SCC efficiency is reduce thickness TI films minimize trivial bulk contribution. However, when reaches ultrathin regime, decreases owing intersurface hybridization. To overcome these contrary effects, we induced dehybridization film by breaking inversion symmetry between surfaces. For grown on an...
The flexible and mixed δ- α-formamidinium lead iodide (FAPbI3) hybrid perovskite thin films fabricated by the sequential vacuum evaporation method (SVE) were studied using THz-wave absorption property. formed FAPbI3 SVE showed typical δ-phase. After annealing for 10 min, we confirmed a state with α-phases observed at 1.62 THz 40% absorptance. In C 1s core-level spectra, found two different chemical states originated from α-FAPbI3. origin of property is assumed significant Pb–I vibration mode...
Hexagonal porous optical fiber without a central defect is proposed and numerically analyzed with the finite element method (FEM) for transmitting terahertz (THz) electromagnetic wave pulse. In experiments, transmission characteristics of polytetrafluoroethylene (PTFE) hexagonal fibers were measured using THz time-domain spectroscopy (THz-TDS) system. To precisely estimate effective material loss (EML), we refractive index absorption coefficient PTFE in range to use them FEM analyses, EML...
Abstract The terahertz (THz)-wave absorption properties in organic-inorganic hybrid perovskite (OHP) materials are investigated with the in-depth development of OHP-based THz applications. In range from 0.5 to 3 THz, OHPs typically show several interesting phonon modes such as transverse, longitudinal, and halogen self-vibrations. To modulate these frequencies, density changes defect-incorporated structures element mixtures were tested confirmed. literature, origin OHP have been mostly...
The frequency-dependent optical constants and electrical conductivities of hydrogen-functionalized single-walled carbon nanotubes (SWNTs) have been measured from the 0.2 to 1.5 THz region using a terahertz time domain spectroscopy. indices refraction sample after hydrogen functionalization were smaller than those before functionalization. experimental results fitted Maxwell–Garnett model, reduction plasma frequency was observed. This can be attributed fact that has reduced number free...