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윤운하(Woon Ha Yoon),강성준(Seong Jun Kang),정양희(Yang Hee Joung) 한국전자통신학회 2016 한국전자통신학회 논문지 Vol.11 No.5
본 논문은 RTP법으로 산화막을 질화시킨 질화산화막으로 MIS 커패시터를 제작하여 avalanche 주입에 따른 캐리어 트랩 특성을 조사하였다. avalanche 주입에 의한 flatband 전압 변화는 두 번의 turn-around가 관찰되었는데 이는 처음 산화막에서 전자 트래핑이 있어나고, 전하 주입에 따라 홀 트래핑에 의한 turn-around 후 다시 전자 트래핑이 일어나는 것을 관찰하였다. 질화 산화막의 캐리어 트랩 파라미터를 결정하기 위하여 실험 결과를 기초로 종류가 다른 여러 트랩을 갖는 계에 대한 캐리어 트래핑을 비교한 결과 실험값과 일치함을 확인하였다. In this paper, the MIS(: Metal-Insulator-Semiconductor) Capacitor with the nitrided-oxide by RTP are fabricated to investigate the carrier trap parameters due to avalanche electron injection. Two times turn-around phenomenon of the flatband voltage shift generated by the avalanche injection are observed. This shows that electron trapping occurs in the oxide film at the first stage. As the electron injection increases, the first turn-around occures due to a positive charge in the oxide layer. After further injection, the curves turns around once again by electron captured. Based on the experimental results, the carrier trapping model for system having multi-traps is proposed and is fitting with experimental data in order to determine trap parameter of nitrided-oxide.
에어로졸 데포지션에 의한 이트리아 필름의 미세구조와 특성
이병국,박동수,윤운하,류정호,한병동,최종진,Lee, Byung-Kuk,Park, Dong-Soo,Yoon, Woon-Ha,Ryu, Jung-Ho,Hahn, Byung-Dong,Choi, Jong-Jin 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.5
Dense crack-free yttria film with 10 $\mu m$ thickness was prepared on aluminum by aerosol deposition. X-ray diffraction pattern on the film showed that it contained the same crystalline phase as the raw powder. Transmission electron microscopy revealed a nanostructured yttria film with grains smaller than 100 nm. Tensile adhesion strength between the film and aluminum substrate was 57.8 $\pm$ 6.3MPa. According to the etching test with $CF_4-O_2$ plasma, the etching rate of the yttria film was 1/100 that of quartz, 1/10 that of sintered alumina and comparable to that of sintered yttria.
50μm급 이트리아 안정화 지르코니아 비드의 미세구조 및 마모 조건에 따른 마모율 분석
김정환,윤세중,한병동,안철우,윤운하,최종진,Kim, Jung-Hwan,Yoon, Sae-Jung,Hahn, Byung-Dong,Ahn, Cheol-Woo,Yoon, Woon-Ha,Choi, Jong-Jin 한국재료학회 2019 한국재료학회지 Vol.29 No.4
This study analyzes the mechanical properties, including the attrition rate, of $50{\mu}m$ size yttria-stabilized zirconia (YSZ) beads with different microstructures and high-energy milling conditions. The yttria distribution in the grain and grain-boundary of the fully sintered beads relates closely to Vickers hardness and the attrition rate of the YSZ beads. Grain size, fractured surfaces, and yttrium distribution are analyzed by electronic microscopes. For standardization and a reliable comparison of the attrition rate of zirconia beads with different conditions, Zr content in milled ceramic powder is analyzed and calculated by X-ray Fluorescence Spectrometer(XRF) instead of directly measuring the weight change of milled YSZ beads. The beads with small grain sizes sintered at lower temperature exhibit a higher Vickers hardness and lower attrition rate. The attrition rate of $50{\mu}m$ YSZ beads is measured and compared with the various materials properties of ceramic powders used for high-energy milling. The attrition rate of beads appears to be closely related to the Vickers hardness of ceramic materials used for milling, and demonstrates more than a 10 times higher attrition rate with Alumina(Hv ~1650) powder than $BaTiO_3$ powder (Hv ~315).
상온 분사 공정에 의한 산화물전도 입자 복합 하이브리드 NTC 서미스터 필름의 제작 및 특성
강주은,류정호,최종진,윤운하,김종우,안철우,최준환,박동수,김양도,Kang, Ju-Eun,Ryu, Jungho,Choi, Jong-Jin,Yoon, Woon-Ha,Kim, Jong-Woo,Ahn, Cheol-Woo,Choi, Joon Hwan,Park, Dong-Soo,Kim, Yang-Do 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.1
Negative-temperature coefficient (NTC) thermistors based on nickel manganite spinel ($NiMn_2O_4$) are widely used for many applications, such as sensors and temperature compensators, due to their good thermistor characteristics and stabilities. However, to achieve thermistors with a high NTC B constant, which is an important figure of merit pertaining to the degree of temperature sensitivity, the activation energy should be high such that high resistivity at ambient temperatures results. To obtain a high B constant and low resistivity, Al and Si modified spinel structured $Ni_{0.6}Si_{0.2}Al_{0.6}Mn_{1.6}O_4$ hybrid thick films with the conducting metal oxide of $LaNiO_3$ were fabricated on a glass substrate by aerosol deposition at room temperature (RT). The NTC-$LaNiO_3$ hybrid thick films showed resistivity as low as < $100k{\Omega}\;cm$ at $90^{\circ}C$, which is one or two orders of magnitude lower than that of the monolithic NTC films, while retaining a high B constant of $NiMn_2O_4$ of over 5500 K when 20 wt% $LaNiO_3$ was added without a post-thermal treatment. These phenomena are explained by the percolation threshold mechanism.
상온 진공 분말 분사 공정을 이용한 다층 박막 소재의 제조 및 전기적 특성
류정호,안철우,김종우,최종진,윤운하,한병동,최준환,박동수,Ryu, Jung-Ho,Ahn, Cheol-Woo,Kim, Jong-Woo,Choi, Jong-Jin,Yoon, Woon-Ha,Hahn, Byung-Dong,Choi, Joon-Hwan,Park, Dong-Soo 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.8
Room temperature powder spray in vacuum process, so called Aerosol deposition (AD) is a room temperature (RT) process to fabricate thick and dense ceramic films, based on collision of solid ceramic particles. This technique can provide crack-free dense thin and thick films with thicknesses ranging from sub micrometer to several hundred micrometers with very fast deposition rates at RT. In addition, this technique is using solid particles to form the ceramic films at RT, thus there is few limitation of the substrate and easy to control the compositions of the films. In this article, we review the progress made in synthesis of piezoelectric thin/thick films, multi-layer structures, NTC thermistor thin/thick films, oxide electrode thin films for actuators or sensor applications by AD at Korea Institute of Materials Science (KIMS) during the last 4 years.
후열처리 공정이 에어로졸 증착법에 의해 제조된 PMN-PZT 막의 미세구조와 전기적 특성에 미치는 영향
한병동,고관호,박동수,최종진,윤운하,박찬,김도연,Hahn, Byung-Dong,Ko, Kwang-Ho,Park, Dong-Soo,Choi, Jong-Jin,Yoon, Woon-Ha,Park, Chan,Kim, Doh-Yeon 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.2
PMN-PZT films with thickness of $5\;{\mu}m$ were deposited on $Pt/Ti/SiO_2/Si$ substrate at room temperature using aerosol deposition process. The films showed fairly dense microstructure without any crack. XRD and TEM analysis revealed that the films consisted of randomly oriented nanocrystalline and amorphous phases. Post-annealing process was employed to induce crystallization and grain growth of the as-deposited films and to improve the electrical properties. The annealed film showed markedly improved electrical properties in comparison with as-deposited film. The film after annealing at $700^{\circ}C$ for 1h exhibited the best electrical properties. Dielectric constant $(\varepsilon_r)$, remanent polarization $(P_r)$ and piezoelectric constant $(d_{33})$ were 1050, $13\;{\mu}C/cm^2$ and 120 pC/N, respectively.
상온 진공 분말 분사법에 의한 NiMn<sub>2</sub>O<sub>4</sub>계 NTC Thermistor 후막제작 및 특성평가
백창우,한귀팡,한병동,윤운하,최종진,박동수,류정호,정대용,Baek, Chang-Woo,Han, Gui-fang,Hahn, Byung-Dong,Yoon, Woon-Ha,Choi, Jong-Jin,Park, Dong-Soo,Ryu, Jung-ho,Jeong, Dae-Yong 한국재료학회 2011 한국재료학회지 Vol.21 No.5
Negative temperature coefficient (NTC) materials have been widely studied for industrial applications, such as sensors and temperature compensation devices. NTC thermistor thick films of $Ni_{1+x}Mn_{2-x}O_{4+{\delta}}$ (x = 0.05, 0, -0.05) were fabricated on a glass substrate using the aerosol deposition method at room temperature. Resistance verse temperature (R-T) characteristics of the as-deposited films showed that the B constant ranged from 3900 to 4200 K between $25^{\circ}C$ and $85^{\circ}C$ without heat treatment. When the film was annealed at $600^{\circ}C$ 1h, the resistivity of the film gradually decreased due to crystallization and grain growth. The resistivity and the activation energy of films annealed at $600^{\circ}C$ for 1 h were 5.203, 5.95, and 4.772 $K{\Omega}{\cdot}cm$ and 351, 326, and 299 meV for $Ni_{0.95}Mn_{2.05}O_{4+{\delta}}$, $NiMn_2O_4$, and $Ni_{1.05}Mn_{1.95}O_{4+{\delta}}$, respectively. The annealing process induced insulating $Mn_2O_3$ in the Ni deficient $Ni_{0.95}Mn_{2.05}O_{4+{\delta}}$ composition resulting in large resistivity and activation energy. Meanwhile, excess Ni in $Ni_{1.05}Mn_{1.95}O_{4+{\delta}}$ suppressed the abnormal grain growth and changed $Mn^{3+}$ to $Mn^{4+}$, giving lower resistivity and activation energy.
상온 진공 분말 분사공정에 의해 제조된 TiO<sub>2</sub> 광촉매 막의 두께변화에 따른 광촉매 특성
김근영,류정호,한병동,최종진,윤운하,이병국,박동수,박찬,Kim, Kun-Young,Ryu, Jung-Ho,Hahn, Byung-Dong,Choi, Jong-Jin,Yoon, Woon-Ha,Lee, Byoung-Kuk,Park, Dong-Soo,Park, Chan 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.12
$TiO_2$ is an environment-friendly semiconducting material, and it has photocatalytic and hydrophilic effect. There are a lot of reports on the photocatalytic characteristics of $TiO_2$, such as organic pollutants resolving, anti-bacterial, and self-purification material. In this paper, $TiO_2$ micron-sized powders were deposited on the glass by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $TiO_2$ photocatalytic thin films were fabricated. The thickness of the films were controlled by changing the number of deposition cycle. Morphologies and characteristics of the AD-$TiO_2$ thin films were examined by SEM, TEM, XRD, and UV-Visible Spectrophotometer. As the thickness of $TiO_2$ films increased, surface roughness increased. By this increment, the reaction area between film and pollutant was enlarged, resulting in better photocatalytic property.
황건태(Geon-Tae Hwang),류정호(Jungho Ryu),윤운하(Woon-Ha Yoon) 한국세라믹학회 2021 세라미스트 Vol.24 No.3
Magneto-mechano-electric (MME) conversion composites composed of distinctive magnetostrictive and piezoelectric materials derive interfacial coupling of magnetoelectric conversion between magnetic and electric properties, thus enabling energy harvesting and magnetic sensing. To demonstrate highperformance MME composites and their applications, various research teams have studied tailoring device structures, enhancing material properties, and developing MME application system. This article reviews the recent research progress of MME composites for energy harvesting and magnetic sensing.