A5026990815- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Ga2O3 and related materials
- 2D Materials and Applications
- MXene and MAX Phase Materials
- Advanced Photocatalysis Techniques
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and devices
- Advanced Memory and Neural Computing
- Conducting polymers and applications
- Pigment Synthesis and Properties
- Graphene research and applications
- Quantum Dots Synthesis And Properties
- Metal and Thin Film Mechanics
- Perovskite Materials and Applications
- TiO2 Photocatalysis and Solar Cells
- Acoustic Wave Resonator Technologies
- Thermodynamic and Structural Properties of Metals and Alloys
- Photorefractive and Nonlinear Optics
- Advanced Thermoelectric Materials and Devices
- Catalysis and Oxidation Reactions
- Copper-based nanomaterials and applications
- Thin-Film Transistor Technologies
- Luminescence Properties of Advanced Materials
Kongju National University
2011-2022
Konyang University
2019
University of Ulsan
2011-2019
Government of the Republic of Korea
2018
Ulsan College
2011
Spectroscopic ellipsometry and x-ray diffraction are used to investigate the metal-insulator transition in V2O5 films. Below above Tc no significant change (001) peak is observed, but both n k spectra undergo remarkable changes over entire photon energy range. The SE XRD results indicate that film undergoes a MIT without structural phase near 280 °C. Further confirmed by measurement of resistance with temperature.
Room-temperature photoluminescence (PL) in V<sub>2</sub>O<sub>5</sub> nanospheres with zero-like dimensional structure was investigated.
Abstract 1 T phase incorporation into 2H-MoS 2 via an optimal electron irradiation leads to induce a weak ferromagnetic state at room temperature, together with the improved transport property. In addition 1T-like defects, on cleaved MoS surface forms concentric circle-type defects that are caused by H/1 transition and vacancies of nearby S atoms Mo atoms. The irradiation-reduced bandgap is promising in vanishing Schottky barrier attaining spintronics device. simple method control improve...
The temperature dependence of the interband transition in an α-V2O5 film was investigated using absorption and photoluminescence spectral measurements at a range 10–300 K. Transmission experimental indicate that has two distinct transitions, implying indirect direct transitions. This result confirmed by spectroscopic ellipsometry. blue shift both transitions with decreasing explained reduction lattice-dilatation effect electron-phonon interaction. PL showed emission near 530 nm is due to film.
The relationship between the first-order metal-insulator transition (MIT) and structural phase (SPT) in VO2 film is analyzed by dielectric function, optical conductivity, plasma energy, electrical conductivity. MIT SPT temperatures films were approximately 68 75 °C, respectively, with an intermediate existing °C. results indicate that not driven SPT.
Abstract Alkali metal halide‐assisted chemical vapor deposition (CVD) methods can produce wafer‐scale uniform monolayer transition dichalcogenides (TMDs). Further defect engineering is necessary to obtain high‐performance functional devices. While has focused on the surface of TMDs or contact property, interface rare and non‐trivial. Based a NaCl‐assisted CVD‐grown large‐scale MoS 2 SiO /Si substrate, trace amount Na cations present, residing at substrate during CVD‐growth process...
By Ne ion sputtering on the single-crystalline MoS2 surface, we demonstrate that S layers sandwiching Mo in top layer are sequentially removed by top-down desulfurization, but intermediate is maintained. Selective desulfurization can be used to control bandgap of switching polarity from n-type p-type conductivity and further inducing metallization. Furthermore, surface also switched controlling hydrogen bonding at/around various sulfur vacancy defects. More importantly, reveal such weakens...
In order to reveal the electron-electron correlation (interaction) effect in a Mott insulator VO2, we measured temperature dependence of thermopower, Hall effect, and Raman spectra VO2 films extracted diverging effective mass from thermoelectric behavior metal-insulator transition (MIT) region, using combination thermopower formula for two-dimensional electron system extended Brinkman-Rice (EBR) model explaining effect. The power is closely fitted by band-filling (ρ) dependent m*/m=1/(1−ρ4)...
A sulfur element is a promising anion dopant for synthesizing new multifunctional materials and exploring unusual physical phenomena. However, owing to its volatility, substitution oxide challenging, thus the sulfurization effects on associated properties have been limitedly studied. Here, facile method perovskite $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ developed demonstrated. thiourea $(\mathrm{C}{\mathrm{H}}_{4}{\mathrm{N}}_{2}\mathrm{S})$ solution used as precursor...
Two-dimensional (2D) metal monochalcogenides have recently attracted significant interest following the extensive and intensive research into transition dichalcogenides (TMDs). However, formation of monochalcogenide remains relatively unstudied. Here, we investigate structural electronic changes MoS2 monolayer by removing top sulfur layer using low-energy He+ ion sputtering. As a result, substoichiometric MoSx surface induces semiconducting to metallic phase transition. Under ambient...
본 연구에서는 RF 파워, 기판의 종류, 산소분압비의 다양한 제작조건으로 마그네트론 스퍼터링법을 이용하여 <TEX>$Ta_{2}O_{5}$</TEX> 박막을 제작하였다. 제작된 박막의 분석을 위해 위상변조방식의 분광타원계를 타원상수를 <TEX>$1.0{\sim}4.0eV$</TEX> 영역에 걸쳐 측정하였고, Tauc-Lorentz 분산관계식을 두께와 광학상수를 분석한 결과 제작조건에 따른 광학상수의 크기와 분간형태의 변화가 나타났다. 또한 분산관계식에 의해 분석된 얻은 투과율 스펙트럼을 UV-Vis 분광광도계에 측정된 값과 비교하여 타원상수 통해 신뢰성을 확인하였다. thin films were deposited by magnetron sputtering method under various power, substrates and oxygen partial pressure. Elliptic constants measured using a phase modulated...
[ <TEX>$V_{2}O_{5}$</TEX> ] 박막의 성장특성을 분석하기 위해 RF 스퍼터링 시스템으로 C-Si 기판에 10 %와 0 %의 산소 분압비로 시료를 제작하였다. 구조적 특성의 분석을 SBM과 XRD 측정을 실시하였고, 위상변조방식의 분광타원계를 이용하여 <TEX>$0.75{\sim}4.0\;eV$</TEX> 범위에 걸쳐 타원상수를 측정하였다. 측정된 타원상수 상용화된 분석용 프로그램인 DeltaPsi2를 이용하여, Double Amorphous 분산관계식으로 최적 맞춤 하였다. SEM과 측정결과 시료의 표면 및 결정 상태는 비정질임을 확인하였고, 타원상수의 분석에 의해 <TEX>$V_{2}O_{5}$</TEX>층의 두께, void비율, 거칠기를 알 수 있었다. 또한 SEM 측정치와 비교한 결과 두 두께와 거칠기의 결과가 잘 일치함을 확인 Optical structure of thin films were analyzed and confirmed, the...
산소분압비에 따른 ZnO 박막의 성장특성을 알아보기 위해 RF 스퍼터링 시스템을 이용하여 <TEX>$0%{\sim}30%$</TEX>의 산소분압비로 박막을 제작하였다. 위상변조방식의 분광타원계를 <TEX>$1.5{\sim}3.8eV$</TEX> 범위에 걸쳐 타원상수를 측정하였고, TL 분산관계식을 최적맞춤한 결과 박막과 표면기칠기층의 두께, void 비율을 알 수 있었고, 알갱이의 크기는 산소분압비의 증가에 따라 그 크기가 작아짐을 있었다. 밴드 갭은 산소유입량의 증가하여 광흡수 특성이 크게 의존함을 알았고, 증가는 결정의 불완전성을 증가시키는 것으로 나타났다. thin films were grown on a glass by sputtering system with power 100W and oxygen partial pressure of <TEX>$0%{/sim}30%$</TEX>. Elliptic constants measured using phase modulated...