A5065283560- Transition Metal Oxide Nanomaterials
- Surface and Thin Film Phenomena
- ZnO doping and properties
- Advanced Memory and Neural Computing
- Advanced Materials Characterization Techniques
- Ga2O3 and related materials
- Ferroelectric and Piezoelectric Materials
- Gas Sensing Nanomaterials and Sensors
- Electronic and Structural Properties of Oxides
- Acoustic Wave Resonator Technologies
- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Semiconductor materials and interfaces
- Magnetic properties of thin films
- Machine Learning in Materials Science
- Microwave Engineering and Waveguides
- Magnetic and transport properties of perovskites and related materials
- Advanced Power Amplifier Design
- Nanopore and Nanochannel Transport Studies
- Perovskite Materials and Applications
- Electrochemical Analysis and Applications
- Polydiacetylene-based materials and applications
- Metamaterials and Metasurfaces Applications
- Fuel Cells and Related Materials
- Glass properties and applications
Soongsil University
2023
Pohang University of Science and Technology
2016-2023
University of Minnesota
2022
Government of the Republic of Korea
2020
Yonsei University
2003-2012
Kyungbok University
1999
One-dimensional atomic chains on Au/Si(557) feature two proximal 1D bands near the Fermi level, which were controversially attributed as a spinon-holon pair of Luttinger liquid. Angle-resolved photoemission shows that only one band is metallic with neighboring gapped at room temperature. Furthermore, even branch found to undergo metal-insulator transition upon cooling, follows mean-field-type behavior. Scanning tunneling microscopy observes apparently unequivocal surface, exhibits...
The epitaxial growth of functional oxides using a substrate with graphene layer is highly desirable method for improving structural quality and obtaining freestanding nanomembranes scientific study, applications, economical reuse substrates. However, the aggressive oxidizing conditions typically used in growing can damage graphene. Here, we demonstrate successful use hybrid molecular beam epitaxy SrTiO 3 that does not require an independent oxygen source, thus avoiding damage. This approach...
Abstract The use of gate bias to control electronic phases in VO 2 , an archetypical correlated oxide, offers a powerful method probe their underlying physics, as well for the potential develop novel devices. Up date, purely electrostatic gating 3‐terminal devices with channel shows limited efficiency due insufficiently induced carrier density and short screening length. Here massive reversible conductance modulation is shown by applying V G at low voltage solid‐state proton (H + )...
In situ exsolution of metal nanoparticles (NPs) is emerging as an alternative technique to deliver thermally stable and evenly dispersed NPs, which exhibit excellent adhesion with conducting perovskite oxide supports. Here we provide the first demonstration that Ni NPs high areal density (∼175 μm-2) fine size (∼38.65 nm) are exsolved from A-site-deficient stannate support (La0.2Ba0.7Sn0.9Ni0.1O3-δ (LBSNO)). The strongly anchored impart coking resistance, Ni-exsolved stannates show...
Dynamically reconfigurable nanoscale tuning of visible light properties is one the ultimate goals both in academic field nanophotonics and optics industry demanding compact high-resolution display devices. Among various efforts incorporating actively optical materials into metamaterial structures, phase-change have been spotlight owing to their tunability wide spectral regions including spectrum. However, modulation intensity has limited with small depth, reflective schemes, a lack profound...
Electronic phase modulation based on hydrogen insertion/extraction is kinetically limited by the bulk diffusion or surface exchange reaction, so slow kinetics has been a fundamental challenge to be solved for realizing faster solid-state electrochemical switching devices. Here we accelerate electronic that occurs insertion in VO2 through vertically aligned 2D defects induced symmetry mismatch between epitaxial films and substrates. By using domain-matching growth of monoclinic with lattice...
A one-dimensional system of Si(111)-(5 x 2)-Au is explored using scanning tunneling microscopy and spectroscopy. The chain Si adatoms called bright protrusions (BP's) found to be semiconducting with an evanescent state in the gap, which originates from adjoining metallic BP-free segments. quantitative analysis shows that decays inverse-Gaussian form, leading appearance a parabolic BP chain, scales its length. Spatial decay suggests quadratic band bending existence Schottky-like potential...
The Si(557) surface with Au adsorbates consists of a well ordered array atomic chains, which exhibit interesting one-dimensional (1D) metallic band structure two nearly half-filled 1D bands. This system was recently found to undergo metal-insulator transition below room temperature [Phys. Rev. Lett. 91, 196403 (2003)]. structural and electronic changes upon the phase have been investigated in detail using scanning tunneling microscopy spectroscopy (STM/STS) guide first-principles...
Abstract Materials displaying metal-insulator transitions (MITs) as a function of external parameters such temperature, pressure, or composition are most intriguing from the fundamental point view and also hold high promise for applications. Vanadium dioxide (VO 2 ) is one prominent examples MIT having prospective applications ranging intelligent coatings, infrared sensing, imaging, to Mott memory neuromorphic devices. The key aspects conditioning possible controllability reversibility...
Abstract Mott threshold switching, which is observed in quantum materials featuring an electrically fired insulator-to-metal transition, calls for delicate control of the percolative dynamics switchable domains on a nanoscale. Here, we demonstrate that embedded metallic nanoparticles (NP) dramatically promote metastability single-crystal-like VO 2 switches. Using model system Pt-NP-VO films, interestingly, Pt NPs provide 33.3 times longer ‘memory’ previous conduction by serving as pre-formed...
$\mathrm{Si}(111)\text{\ensuremath{-}}5\ifmmode\times\else\texttimes\fi{}2\text{\ensuremath{-}}\mathrm{Au}$ is investigated in detail using scanning tunneling microscopy and spectroscopy at $78\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. It shown that topographic features STM images are strongly dependent on bias voltages, including a new atomic feature, V unit. Detailed investigations of local distributions electronic states by microscopy, point spectroscopy, current imaging suggest extensive...
Abstract Unlike the substitutional dopants, interstitial hydrogen effectively supplies significant amount of carriers in empty narrow d band correlated electronic systems by reversibly adding it into sites. Here, is demonstrated that hydrogenated VO 2 , a heavily insulating phase with 3d configuration, can be thermodynamically stabilized topotactically preserving its lattice framework regardless facet direction epilayers. However, kinetics modulation and response out‐of‐plane expansion are...
Hydrogen spillover is a catalytic process that occurs by surface reaction and subsequent diffusion to reversibly provide massive amount of hydrogen dopants in correlated oxides, but the mechanism at oxides with metal catalyst are not well understood. Here we show significant oxygen released from VO2 films during spillover, contrary well-established observation formation interstitials bulk part films. By using ambient-pressure X-ray photoelectron spectroscopy, prove vacancies consequence...
Several metastable polymorphs, diverse crystal structures with the same chemical formula, could be accessed through epitaxial interfaces low energy between film and symmetry-matched substrates. Here, we fabricated tungsten oxide (WO3) nanoscaffolds composed of hexagonal WO3 (h-WO3)/monoclinic (m-WO3) modulated proportions these phases by tuning W arrival rate during growth. The nanoscaffold is vertically aligned coherent interphase boundaries h-WO3 m-WO3; this structure leads to persistence...
In this paper, piezoelectric properties of PMN-PZT ceramics were investigated as a function CeO/sub 2/ addition from 0 mole% to 2.0 mole%. The grain size was decreased and the shape it more uniform with 2/. At specimen 0.25 2/, mechanical quality factor (Q/sub m/) electromechanical coupling coefficient (K/sub p/) showed excellent results 1,792 0.518, respectively. electric coercive field increased curie temperature A Rosen type-piezoelectric transformer has been designed fabricated using...
As the channel lengths of electronic devices are scaled down to nanometer range, conventional methods evaluate charge-carrier mobility approach a technical limit that is imposed by interfering effects electrode and forcing field. In this study, we demonstrate electron spectroscopy provides additional (yet hidden) information on unipolar charge transport, which free from problems. We estimated effective diffusion current through target sample allows measurement precise enough (10−4 cm2/V s)...
In this study, we designed a CMOS wideband low-noise amplifier (LNA) operating at 24.0-41.0 GHz. The optimization techniques of the first-stage transistor size tuning and high-pass filter (HPF) structure were used in consideration noise characteristics high frequency. Finally, diode linearizer technique third stage to improve linearity LNA, considering that bandwidth are trade-off relationship. To verify feasibility proposed design techniques, three-stage LNA using 65-nm RFCMOS process....
This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulation power supplies. operates in the second thickness resonant vibration mode. Accordingly its frequency is higher than 1 MHz. Output our past work was low if input and output parts consisted single layer. In order to overcome this problem, research suggests method, which both part have 2-layered ceramics. The size 20 mm width length, 1.4 thickness, respectively. To design high efficient...
In article number 1802003, Ji Young Jo, Junwoo Son, and co-workers apply a gate bias to solid-state proton conductors control the electronic phases in VO2 channel, yielding reversible phase transition between metal insulator. The proton-induced occurs by giant modulation of out-of-plane lattice parameters. results demonstrate potential for devices that use ionic/electronic coupling.