• 한국세라믹학회지
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• 제40권2호
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• pp.153-158
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• 2003

Photosensitive sol solution을 이용한 self pattern된 박막은 photoresist/dry etching process에 비해 박막의 제조과정이 간단하다는 장점을 가지고 있다. 이 연구에서는 강유전성 메모리소자의 산화물 전극재료로 사용되고 있는 La$_{0.5}$Sr$_{0.5}$CoO$_3$(LSCO)극 photosensitive sol solution을 이용하여 spin coating법으로 제조하였으며 출발원료는 La-2methoxyethoxide, Sr-ethoxide, Co-2methoxyethoxide를 사용하였다. LSCO gel 박막에 UV 노광시간을 증가시킴에 따라 M(metal)-O-M 결합이 생성되면서 metal $\beta$-diketonate의 UV 흡수 피크 강도는 감소되었고 LSCO gel 박막에 UV조사에 따른 용해도 차이가 생기면서 fine patterning 을 얻을 수 있었다. 68$0^{\circ}C$ 이상의 온도로 대기 중에서 열처리된 LSCO 박막은 perovskite 상을 나타내었고 74$0^{\circ}C$에서 가장 낮은 비저항값(4$\times$10￣$^3$Ωcm)을 얻을 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제23권2호
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• pp.10-13
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• 2021

Superconductor-ferromagnet thin film heterostructure is an ideal system for studying the interplay between superconductivity and ferromagnetism. These two antagonistic properties combined in thin film heterostructure create interesting proximity effects such as spin-triplet superconductivity. Thin film heterostructure of optimally doped La_2-xSr_xCuO₄(LSCO) cuprate superconductor and SrRuO₃(SRO) ruthenate ferromagnet has been grown by pulsed laser deposition. Its temperature-dependent resistivity and Hall effect measurements show that our LSCO/SRO heterostructure has both superconductivity and ferromagnetism. In the Hall effect measurement results, we find additional hump-like structures appear in the anomalous Hall effect signal in the vicinity of superconducting transition. We conclude that giant magnetoresistance of the LSCO layer distorts the AHE signal, which results in a hump-like structure.

• 한국세라믹학회지
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• 제41권1호
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• pp.13-18
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• 2004

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrodes were prepared on ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) thin films by spin coating method using photosensitive sol-gel solution. Self-patterning technique of photosensitive sol-gel solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. Lanthanum(III) 2-methoxyethoxide, Stronitium diethoxide. Cobalu(II)2-methoxyethoxide were used as starting materials for LSCO electrode. UV irradiation on LSCO thin films lead to decrease solubility by M-O-M bond formation and the solubility difference allows us to obtain self-patternine. There was little composition change of the LSCO thin films between before leaching and after leaching in 2-methoxyethanol. The lowest resistivity of LSCO thin films deposited on $SiO_2$/Si substrate was $1.1{\times}10^{-2}{\Omega}cm$ when the thin film was ennealed at $740^{\circ}C$. The values of Pr/Ps and 2Pr of LSCO/SBT/Pt capacitor on the applied voltage of 5V were 0.51, 8.89 ${\mu}C/cm^2$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.214-214
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• 2010

The 0.65Pb($Mg_{1/3}Nb_{2/3})O_3-0.35PbTiO_3$ (PMN-PT) thin films with $La_{0.5}Sr_{0.5}CoO_{3-\delta}$ (LSCO) bottom electrodes were grown on $CeO_2$/YSZ/Si(001), Pt/$TiO_2$/Si and $SrTiO_3$ (STO) substrates using conventional pulsed laser deposition (PLD) at a substrate temperature of $550^{\circ}C$. Since generally the crystallographic orientation of the bottom electrode induces the orientation of the films deposited on it, it allows us to observe the influence of the PMN-PT film orientation on the electrical properties. Phi scan done on PMN-PT/LSCO thin films shows epitaxial behavior of the films grown on sto substrates and $CeO_2$/YSZ buffered Si(001) substrates, and (110) texture on Pt/$TiO_2$/Si substrates. Polarization-electricfield (P-E) measurement shows good hysteresis behavior of PMN-PT films with remnant polarization of 18.2, 8.8, and $4.4{\mu}C/cm^2$ on $CeO_2$/YSZ/Si, Pt/TiO2/Si and STO substrates respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.116-119
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• 2003

Self-patterning of thin films using photosensitive sol solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. In this study, ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) and $La_{0.5}Sr_{0.5}CoO_3$(LSCO)thin films have been prepared by spin coating method using photosensitive sol solution. $Sr(OC_2H5)_2$, $Bi(TMHD)_3$ and $Ta(OC_2H)_5)_5$ were used as starting materials for SBT solution and $La(OCH_2CH_2OCH_3)_3$, $Sr(OC_2H_5)_2$, $CO(OCH_2CH_2OCH_3)_2$ were used for LSCO solution. Solubility difference by UV irradiation on LSCO thin film allows to obtain a fine patterning due to M-O-M bond formation. The lowest resistivity($4{\times}10^{-3}{\Omega}cm$) of LSCO thin films was obtained by annealing at $740^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제27권5호
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• pp.297-302
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• 2014

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrode thin films with a resistivity of ~ 1,600 ${\mu}{\Omega}cm$ were grown on c-$Al_2O_3$ (0001) substrate. $ZnSnO_3$ (ZTO) thin films with different thicknesses were directly grown on LSCO/c-$Al_2O_3$ (0001) substrates at a substrate temperature that ranged from 550 to $750^{\circ}C$ using Pulsed Laser Deposition (PLD). The secondary phase $Zn_2SnO_4$ occurred during the growth of ZTO films and it became more significant with further increasing substrate temperature. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization and coercive field of 0.05 ${\mu}C/cm^2$ and 48 kV/cm, respectively, were obtained in the ZTO film grown at $700^{\circ}C$ in 200 mTorr.

• Bulletin of the Korean Chemical Society
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• 제29권12호
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• pp.2325-2326
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• 2008

• 한국세라믹학회지
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• 제35권7호
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• pp.647-647
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• 1998

비대칭적인 전극 구조를 가지는 Pb(Zr,Ti)$O_3$(PZT) 박막의 비대칭적인 스위칭 특성을 연구하기 위해 Pulsed Laser Deposituin(PLD)방법으로 $LaAlO_3$ 기판 위에 (La,Sr)$CoO_3$/Pb(Zr,Ti)$O_3$/(La,Sr)$CoO_3$(LSCO) 다층구조를 성장시켰다. PZT 박막 캐시터의 전극이 모두 같은 조성일 때, 즉 $(La_0.5Sr_0.5)CoO_3$(LSCO)일 때 PZT 박막의 이력곡선은 대칭성을 보여주고 있다. 그러나 산화물 전극의 조성이 변할 때 PZT 박막 캐패시터는 비대칭성을 보여주고 있다. $LaCoO_3(LCO)$를 상층 전극, $La_0.5,Sr_0.5)CoO_3$(LSCO)를 하층 전극으로 사용하였을 때 이력 곡선은 음의 방향으로 분극된 상태가 불안정 하여 음의 잔류 분극의 완화 현상을 보여준다. 반면 상층 전극이 LSCO, 하층 전극이 LCO인 PZT 박막 캐패시터는 양의 방향의 분극 상태가 불안정하여 양의 잔류 분극이 완화현상을 보여준다. 이러한 이력 곡선의 완화 현상은 LCO/PZT 계면에서의 전자 밴드 구조의 변형에 의한 내부 전계의 형성 때문이라 생각할 수 있다. 내부 전계는 LCO/PZT와 LSCO/PZT 계면에서의 전자 밴드 구조의 변형에 의한 내부 전계의 형성 때문이라 생각할 수 있다.내부 전계는 LCO/PZT 계면에서의 인가된 전압 강하 차이에 의해 발생되며 전압 강하는 각각의 계면에서 0.6V와 -0.12V의 크기를 갖는다.

• 한국진공학회지
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• 제8권4A호
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• pp.425-431
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• 1999

$Pb(Zr_{0.52}, Ti_{0.48})O_3$ (PZT) thick films as an actuating material with conducting oxides, $(La_{0.5}Sr_{0.5}) CoO_3$ (LSCO), have been fabricated by sol-gel method for Optical Micro-Electro-Mechanical System (MEMS) devices, in which PZT/LSCO/SiO2 structures were used. In order to improve the adhesion to LSCO solution in order to enhance the wetting behavior of a water-based LSCO precursor solution and further to improve the adhesion between LSCO and $SiO_2$ layers. PZT films were made using 1-3 propanediol based precursor solution which has a high viscosity and a boiling point appropriate for thick film fabrication. In the precursor solution, Ti-propoxied and Zr-propoxied are partially substituted with acetylacetone to achieve the solution stability while maintaining reactivity. Crack free PZT films (0.8~1$\mu\textrm{m}$) have been successfully fabricated at crystallization temperatures above $700^{\circ}C$. Dielectric constants and dielectric losses of the PZT films were 900~1200and 2~5%, respectively. Piezoelectric constant $d_{33}$ of the PZT films constrained by a substrate were 200pm/V at 100kV/cm.

• 대한기계학회논문집B
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• 제30권12호
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• pp.1211-1217
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• 2006

This study is focused on oxidation prevention of STS430, which is generally used as solid oxide fuel cell(SOFC) interconnect at intermediate operating temperatures with oxidation-proof coatings. Inconel, $La_{0.6}Sr_{0.4}CoO_3(LSCo)$ and $La_{0.6}Sr_{0.4}CoO_3(LSCr)$ were chosen as coating materials. Using a radio frequency magnetron sputtering method, each target material was deposited as thin film on STS430 and was analyzed to find out favorable conditions. In this study, LSCr-coated STS430 can reduce electrical resistance to 1/3 level, compared with uncoated STS430. Also, long-term durability test at $700^{\circ}C$ for 1000 hours tells that LSCr thin layer performs an important role to prohibit serious degradations. Superior oxidation-resistant characteristic of LSCr-coated STS430 is attributed to the inhibition of spinel structure formation such as $MnCr_2O_4$.