• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.983-989
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• 2005

[ $PZT(Pb(Zr,Ti)O_3)$ ] thin films were deposited by multi-target reactive sputtering method on $RuO_2$ substrates. Pure perovskite phase PZT films could be obtained by introducing Ti-oxide seed layer on the $RuO_2$ substrates prior to PZT film deposition. The PZT films deposited on the $RuO_2$ substrates showed highly voltage-shifted hysteresis loop compared with the films deposited on the Pt substrates. The surface of $RuO_2$ substrate was found to be reduced to metallic Ru in vacuum at elevated temperature, which caused the formation of oxygen vacancies at the initial stage of PZT film deposition and gave rise to the voltage shift in the P-E hysteresis loop of the PZT capacitor. The fatigue characteristics of the PZT capacitors under unipolar wane electric field were different from those under bipolar wane. The fatigue test under unipolar wane showed the increase of polarization. It was thought that the ferroelectric domains which had been pinned by charged defects such as oxygen vacancies and the charged defects were reduced in number by combining with the electrons injected from the electrode under unipolar wave, resulting in the relaxation of the ferroelectric domains and the increase of polarization.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.394-397
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• 2001

In this paper, in-situ deposited $Ru/RuO_2$ bottom electrodes have been investigated as new bottom electrodes for PZT thin film capacitor application. As a comparison, structural and electrical properties of PZT thin films on Pt/Ti and $RuO_2$ bottom electrodes are also investigated. The use of $Ru/RuO_2$ hybrid electrodes showed better electrical properties in compression with $RuO_2$ bottom electrode. With increasing Ru electrode thickness, the PZT thin films showed preferred orientation along the (110) direction and and leakage current of PZT thin films were improved. The PZT thin films on Ru (100nm)/$RuO_2$ electrodes exhibited excellent ferroelectric properties such as remant polarization and coercive field of $7.2C/cm^2$ and 46.35 kV/cm, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.394-397
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• 2001

In this paper, in-situ deposited Ru/RuO$_2$ bottom electrodes have been investigated as new bottom electrodes for PZT thin film capacitor application. As a comparison, structural and electrical properties of PZT thin films on Pt/Ti and RuO$_2$ bottom electrodes are also investigated. The use of Ru/RuO$_2$ hybrid electrodes showed better electrical properties in compression with RuO$_2$ bottom electrode. With increasing Ru electrode thickness, the PZT thin films showed preferred orientation along the (110) direction and leakage current of PZT thin films were improved. The PZT thin films on Ru (100nm)/RuO$_2$ electrodes exhibited excellent ferroelectric properties such as remant polarization and coercive field of 7.2 C/$\textrm{cm}^2$ and 46.35 kV/cm, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.85-85
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• 1999

Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT)는 높은 유전율로 인해 강유전체 메모리 소자의 응용을 위한 연구가 되고 있으며 또한 전왜(electrostrictive)성을 갖고 있어 이력현상을 갖지 않음으로 최근 들어 미세전기기계소자(MEMS)로의 연구가 활발히 되고 있다. 본 연구에서는 MEMS 소자로서의 응용을 위해 저응력 SiNx가 형성된 Si 기판위에 Pt 전극 혹은 산화물 전극 SrRuO3를 갖는 PMN-PT 박막 캐패시터를 제조하였다. 박막 하부의 구조는 금속전극의 경우 Pt/Ti/LTO/SiNx/Si이고 산화물전극은 SrRuO3/Ru/SiNx/Si의 구조를 갖는다. PMN-PT 박막은 alkoxide를 기반으로 회전 coating 방법을 사용하여 박막 하부층의 변화를 주어서 성장시켰다. PMN-PT 용액의 합성은 분말합성법에서 사용하는 columbite 방법을 응용하여 상대적으로 반응정도가 낮은 Mg를 Nb와 우선 반응하여 Mg-Nb solution을 얻고 Pb-acetate 용액과 합성하여 PMN을 제조한 후 PT를 반응시켜서 제조하였다. PMN-PT 박막에서 동일한 공정조건 하에서 박막 하부층의 구조에 따라서 PMN-PT 박막의 조성이 A2B2O6의 조성을 가지는 파이로클러어상이 형성되거나 또는 ABO3인 페로브스카이트상이 형성되는 것을 관찰하였다. 금속 전극인 Pt를 하부전극으로 사용한 경우는 혼재상이 형성되어 패로브스카이드 PMN-PT를 얻기 위해 seed layer로서 PbTiO3를 사용하였으며 이러한 seed layer 위에 형성된 PMN-PT를 형성하는 경우 rutile 구조인 RuO2 위에 성장시킨 PMN-PT는 파이로클로어와 페로브스카이트의 혼재상이 얻어졌으나 pseudo-perovskite 구조인 SrRuO3 박막 위에 형성된 PMN-PT 박막에서는 페로브스카이트가 주된 상으로 얻어졌다. 즉 하부층(전극 또는 seed layer)으로 perovskite 구조를 갖는 박막을 형성하게 되면 페로브스카이트를 갖는 PMN-PT 박막을 얻을 수 있었다. 전기적인 특성은 상부전극으로 Pt를 사용하여 HP 4194A로 측정을 하였다. PT seed layer를 포함한 PMN-PT 박막은 유전상수 1086과 유전손실 2.75%을 가졌다.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.471-477
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• 2016

In this research, the Ir supported $TiO_2$ (P25) catalyst was prepared by precipitation method for oxygen evolution reaction. The $Ir/TiO_2$ catalyst was synthesised by reduction reaction using reducing agent. Physiochemical characterizations of synthesized $Ir/TiO_2$ catalyst was studied by means of SEM, EDS mapping, TEM and XRD. The Electrochemical characterizations were tested by using the technique of CV and LSV by RDE and Potentiostat. Physicochemical properties were characterized with XRD where Iridium metal morphology and Ir(111) and Ir(222) peaks were founded. $Ir0.2Ru0.8O_2$ exhibited higher OER activity than $Ir0.5Ru0.5O_2$ followed by $Ir/TiO_2$ and $IrO_2$.

• 전기학회논문지
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• 제67권4호
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• pp.543-548
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• 2018

Ferroelectric $Bi_4Ti_3O_{12}$ films were deposited on $SrTiO_3(100)$ and Si(100) substrate by using conductive $SrRuO_3$ films as underlayer, and their ferroelectric and electrical properties were investigated depending on crystal structure and orientation. C-axis oriented $Bi_4Ti_3O_{12}$ films were grown on well lattice-matched pseudo-cubic $SrRuO_3$ films deposited on $SrTiO_3(100)$ substrate, while random-oriented polycrystalline $Bi_4Ti_3O_{12}$ films were grown on $SrRuO_3$ films deposited on Si(100) substrate. The random-oriented polycrystalline film showed a good ferroelectric hysteresis property with remanent polarization ($P_r$) of $9.4{\mu}C/cm^2$ and coercive field ($E_c$) of 84.9 kV/cm, while the c-axis oriented film showed $P_r=0.64{\mu}C/cm^2$ and $E_c=47kV/cm$ in polarizaion vs electric field curve. The c-axis oriented $Bi_4Ti_3O_{12}$ film showed a dielectric constant of about 150 and lower thickness dependence in dielectric constant compared to the random-oriented film. Furthermore, the c-axis oriented $Bi_4Ti_3O_{12}$ film showed leakage current lower than that of the polycrystalline film. The difference of ferroelectric properties in two films was explained from the viewpoint of depolarization effect due to orientation of spontaneous polarization and layered crystal structure of bismuth-base ferroelectric oxide.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.182-183
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• 2009

플라즈마 원자층 증착법을 이용하여 Ru-TiN 빅막을 합성하였다. 박막 내 Ru의 함량은 Ru의 unit-cycle의 수에 따라 선형적으로 증가하였으며, Ru 함량이 증가함에 따라 박막의 비저항을 $3700{\mu}{\Omega}{\cdot}cm$에서 $190{\mu}{\Omega}{\cdot}cm$까지 자유롭게 조절할 수 있었다. Ru의 함량이 0.40 이상인 경우, Ru과 TiN 두물질이 교차 증착되어 서로의 결정 성장을 충분히 억제함으로서, 비정질구조를 가짐을 확인할 수 있었다. 또한, $O_2$ 분위기에서 열처리를 진행한 결과, Ru의 조성비가 0.40이상인 경우 $700^{\circ}C$까지 면저항의 변화가 거의 없음을 확인할 수 있었다.

• 한국결정성장학회지
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• 제8권2호
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• pp.221-226
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• 1998

$RuO_2$ 하부전극 상에 형성된 $(Ba, Sr)TiO_3$[BST] 박막의 물성을 향상시키기 위하여 비정질 BST층(30, 70nm)을 $RuO_2$와 BST사이에 증착하여 2중 BST구조를 형성시켰다. 비정질 BST층의 도입을 통해, BST박막의 평균 입도가 증가하고, 표면 거칠기가 감소하여 전체 BST 박막의 미세구조와 표면 mophology가 단일 BST박막에 비해 상당한 변화가 발생함을 확인하였다. 30nm의 비정질측이 적용된 BST박막의 경우, 하부기판의 영향으로부터 비교적 자유로운 미세구조를 갖는 BST 박막이 형성되었다. 2중 BST 박막의 경우 유전상수는 340, 누설전류는 $6.85{\times}10^{-7}A/{\textrm}{cm}^2$로서 비정질층을 갖지 않는 단일 BST 박막에 비하여(유전상수: 152, 누설전류: $1.25{\times}10^{-5}A/{\textrm}{cm}^2$)놀라운 전기적 특성의 향상이 이루어짐을 확인하였다.

• 상하수도학회지
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• 제33권1호
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• pp.31-41
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• 2019

Volatile organic compounds(VOCs) are toxic carcinogenic compounds found in wastewater. VOCs require rapid removal because they are easily volatilized during wastewater treatment. Electrochemical advanced oxidation processes(EAOPs) are considered efficient for VOC removal, based on their fast and versatile anodic electrochemical oxidation of pollutants. Many studies have reported the efficiency of removal of various types of pollutants using different anodes, but few studies have examined volatilization of VOCs during EAOPs. This study examined the removal efficiency for VOCs (chloroform, benzene, trichloroethylene and toluene) by oxidization and volatilization under a static stirred, aerated condition and an EAOP to compare the volatility of each compound. The removal efficiency of the optimum anode was determined by comparing the smallest volatilization ratio and the largest oxidization ratio for four different dimensionally stable anodes(DSA): Pt/Ti, $IrO_2/Ti$, $IrO_2/Ti$, and $IrO_2-Ru-Pd/Ti$. EAOP was operated under same current density ($25mA/cm^2$) and electrolyte concentration (0.05 M, as NaCl). The high volatility of the VOCs resulted in removal of more than 90% within 30 min under aerated conditions. For EAOP, the $IrO_2-Ru/Ti$ anode exhibited the highest VOC removal efficiency, at over 98% in 1 h, and the lowest VOC volatilization (less than 5%). Chloroform was the most recalcitrant VOC due to its high volatility and chemical stability, but it was oxidized 99.2% by $IrO_2-Ru/Ti$, 90.2% by $IrO_2-Ru-Pd/Ti$, 78% by $IrO_2/Ti$, and 75.4% by Pt/Ti anodes The oxidation and volatilization ratios of the VOCs indicate that the $IrO_2-Ru/Ti$ anode has superior electrochemical properties for VOC treatment due to its rapid oxidation process and its prevention of bubbling and volatilization of VOCs.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.865-869
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• 2002

The structural and electrical properties of PZT (lead zirconate titante) thin films grown on Pt (platinum) and Ru/Ru $O_2$(ruthenium/ruthenium oxide) electrodes were investigated. Thin films of PZT were deposited on a variety of electrodes using the rf-magnetron sputtering process. PZT films exhibited polycrystalline structure with strong PZT (100) plane and weak (211) plane for an optimizied Pt electrode and (100), (101), (111), (200), (210), (211) planes for Ru/Ru $O_2$. Switching polarization versus fatigue characteristic of Pt/Ti electrodes showed 20% degradation up to 1 $\times$ 10$_{9}$ cycles. No significant fatigue was observed in the films on Ru/Ru $O_2$ electrodes up to Ix109 test cycles. The results show that the new Ru/Ru $O_2$ bottom electrodes are expected to reduce the degradation of ferroelectric fatigue.