• 한국세라믹학회지
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• 제47권1호
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• pp.61-65
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• 2010

Ultrathin atomic layer deposition (ALD) coatings were found to enhance the performance of lithium-ion batteries (LIBs). Previous studies have demonstrated that $LiCoO_2$ cathode powders coated with metal oxides with thicknesses of $\sim100-1000{\AA}$ grown using wet chemical techniques improved LIB performance. In this study, $LiCoO_2$ powders were coated with conformal $Al_2O_3$ ALD films with thicknesses of only $\sim3-4{\AA}$ established using 2 ALD cycles. The coated $LiCoO_2$ powders exhibited a capacity retention of 89% after 120 charge-discharge cycles in the 3.3~4.5 V (vs. $Li/Li^+$) range. In contrast, the bare $LiCoO_2$ powders displayed only a 45% capacity retention. This dramatic improvement may result from the ultrathin $Al_2O_3$ ALD film acting to minimize Co dissolution or to reduce surface electrolyte reactions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1722-1724
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• 1996

Enhancing the electrical conductivity of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir-Blodgett(LB) technique has recently been attracted as out of the ways of deposition ultrathin films. We have studied manufacturing conditions and physical properties of Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB films made by Kuhn type apparatus. A ${\pi}-A$ isotherm shows that a limiting area is around $180{\AA}^2/molecule$ and a proper surface pressure for a deposition is around 22mN/m. A transfer ratio shows that Hexadecyl Dipyridinium-$(TCNQ^-)_2$ is able to be deposited as an Y-type. UV /visible absorption spectra shows that TCNQ dimer peak is apeared at about 600nm in LB films. In solution, $TCNQ^-$ peak is observed at about 400nm and charge transfer band at $830{\sim}900nm$. A horizontal conductivity of the Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB film is about $10^{-7}(S/cm)$.

• 한국위성정보통신학회논문지
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• 제10권3호
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• pp.89-93
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• 2015

본 연구에서는 이온빔 처리된 $HfO_2$ 박막을 이용한 액정디스플레이의 프리틸트각을 제어함으로써, 작은 구동전압에서도 안정적으로 구동할 수 있는 디스플레이 소자에 응용할 수 있는 특성을 연구하였다. $HfO_2$ 박막의 원자 수준의 증착을 통해서 높은 유전율의 박막을 제조할 수 있었으며, 이는 저전력 구동을 위해서 필수적인 요소라고 생각한다. 또한 이러한 $HfO_2$ 박막의 액정배향성을 확인하여 균일한 액정배향을 통해서 디스플레이 소자로의 응용가능성을 확인하였다. 특히 $HfO_2$ 박막에서의 액정배향성에 대해서 액정배향의 대표적인 특성인 프리틸트각의 제어를 실험을 통해서 확인하였다. 실험결과 이온빔처리를 한 $HfO_2$ 박막에서의 액정배향의 특성을 접촉각특성을 대표화하여 정량화 할 수 있었다. 본 연구의 결과 액정의 배향성 확보 및 프리틸트각을 제어할 수 있는 고유전율 $HfO_2$ 박막의 제조가 가능한 것을 확인할 수 있었으며, 고유전율 특성에서 기인하는 저전력 구동의 가능성을 확인할 수 있었다.

• 한국진공학회지
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• 제16권5호
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• pp.311-321
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• 2007

NiO 극초박막을 Ag(001) 단결정 위에 성장하는 과정에서 발생하는 화학 결함들을 X선 광전자 분광법을 이용하여 연구하였다. 특히 박막 두께, 산소 분압, 물 분압, 기판 온도 등을 잘 제어한 성장 환경에서 얻어진 O 1s, Ni 2p 스펙트라의 분석을 통하여 NiO 극초박막 성장 시 형성되는 화학 결함들의 정체를 일관성 있게 밝혀내었다. 이를 통하여 결함 밀도를 최소화 할 수 있는 최적의 성장 조건을 제안할 수 있게 되었다.

• 한국응용과학기술학회지
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• 제12권1호
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• pp.125-131
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• 1995

Ultra thin films of Tetra-3-hexadecylsulphamoylcopperphthalocyanine(HDSM-CuPc) were formed on various substrates by Langmuir-Blodgett method, where HDSM-CuPc was synthesized by attaching long-chain alkylamine(hexa-decylamine) to CuPc. The reaction product was identified with FT-IR, UV-visible absorption spectroscopies, elemental analysis and thin layer chromatography. The formation of Ultrathin Langmuir-Blodgett(LB) films of HDSM-CuPc was confirmed by FT-IR and UV-visible spectroscopies. A quartz piezoelectric crystal coated with LB films of HDSM-CuPc was examined as a gas sensor for $N0_2$ gas. HDSM-CuPc LB films were transferred to a quartz crystal microbalance(QCM) in the form of Z-type multilayers. Response characteristics of film-coated QCM to $NO_2$ gas concentrations over a range of $100{\sim}600ppm$ have been tested with a thickness of $5{\sim}20$ layers of HDSM-CuPc. Changes in frequency by adsorption of $NO_2$ were increased With the number of LB layers and $NO_2$ concentration, but the response time was slow.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.158-158
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• 2009

This paper focuses on improving organic thin film transistor (OTFT) characteristics by controlling the self-organization of pentacene molecules with an alignable high-dielectric-constant film. The process, based on the growth of pentacene film through high-vacuum sublimation, is a method of self-organization using ion-beam (IB) bombardment of the $HfO_2/Al_2O_3$ surface used as the gate dielectric layer. X-ray photoelectron spectroscopy indicates that the IB raises the rate of the structural anisotropy of the $HfO_2/Al_2O_3$film, and X-ray diffraction patterns show the possibility of increasing the anisotropy to create the self-organization of pentacene molecules in the first polarized monolayer. An effective mobility of $2.3{\times}10^{-3}cm^2V^{-1}s^{-1}$ was achieved, which is significantly different from that of pentacene films that are not aligned. The proposed OTFT devices with an ultrathin $HfO_2$ structure as the gate dielectric layer were operated at a gate voltage lower than 5 V.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.287-296
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• 2000

We have developed a three-axis configurational in situ SMOKE apparatus by which three-dimensional vector magnetization reversal processes are studied for ultrathin Co films grown on a Pd (111) single crystal in the thickness range of spin-reorientation transition. This study provides a better understanding of magnetization reversal motions with the knowledge of 3 components of magnetization vector at the transition of an easy axis of magnetization from the film normal at 5 ML Co to in-plane at 6 ML Co (ML notes monolayer). For a 5.25 ML Co, it was observed that a slightly canted magnetization vector from the film normal rotated in the film plane under an applied field direction parallel to the film normal.

• Journal of Magnetics
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• 제6권2호
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• pp.53-56
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• 2001

We have developed a three-axis configurational in situ SMOKE apparatus by which three-dimensional vector magnetization reversal processes are studied for ultrathin Co films grown on a Pd (111) single crystal in the thickness range of spin reorientation transition. This study provides a better understanding of magnetization reversal motions with the knowledge of three components of the magnetization vector at the transition of an easy axis of magnetization from the film normal at 5 ML Co to in-plane at 6 ML Co (ML denotes monolayer). For a 5.25 ML Co, it was observed that a slightly canted magnetization vector from the film normal rotated in the film plane under an applied field direction parallel to the film normal.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.77-80
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• 1995

Enhancing the electrical conductivity of the ultrathin organic films using Langmuir-Blodget technique is important step for the developement of molecular electronic device. The Octadecylviologen-TCNQ was synthesized with Octadecylviologen-Bromide an Lithium TCNQ Sine Octadecylviologen-TCNQ has two TCNQ snion radicals, the conductivity of LB film is expected to increase. The $\pi$-A isotherm showed that the limiting area was 150${\AA}$$\^$2/ molecule and the silid-like transition surface pressure was 25 mN/m. The electronic transition of the TNCNQ anion radical was observed at 400 nm. Intermolecular charge transfer absorption was observed at 600nm and 850~1050 nm which ay resulted from the TCNQ anion radical dimer formation. The electrical conductivity of the viologen -TCNQ LB film was 10$\^$-6/cm This values was 100 times higher than that of the quinolinium-TCNQ and pyridinium-TCNQ LB films.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.240-243
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• 1995

The basic electrochemical and photochemical behavior of ultrathin mono- and hetero-type LB film of amphiphilic Ru bipyridine complex adsorbed on ITO electrode by the Langmuir- Blodgett(LB) method as monolayer and alternating multilayer state. With theoretical equation of cyclic voltammetry for redox species, the cyclic voltammogram were simulated successfully taking account the interaction parameters. We could fit almost all measured voltammograms with k$^{\circ}$=72s$\^$-1/, ${\alpha}$$\sub$a/=0.44, ${\alpha}$$\sub$c/=0.54, $\Gamma$$\sub$T/=1.4${\times}$10$\^$-10/, k=0.015s$\^$-1/ values. The AFM images of mono and hetero type LB film surfaces on ITO were also studied.