• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.5
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• pp.313-322
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• 2001

The effects of Zr/Ti concentration ratio in PLZT (10/y/z) thin films prepared by sol-gel method are investigated for the NVFRAM application. Rosette and pyrochlore phase are observed in PLZT (10/40/60) thin film and the (100) orientation, the grain size, and the surface roughness of PLZT thin films increase due to the increase of Ti amount in Zr/Ti concentration ratio. As Ti amount of Zr/Ti concentration ratio increases, the dielectric constants at 10KHz decrease from 600 to 400, while the loss tangents increase from 0.028 to 0.053 and the leakage current densities at 170 kY/cm decrease from 1.64$\times$10$^{-6}$ to 1.26$\times$10$^{-7}$ A/$\textrm{cm}^2$. In the results of hysteresis loops measured at $\pm$ 170 ㎸/cm, the remanent polarization and the coercive field increase from 6.62 to 12.86 $\mu$C/$\textrm{cm}^2$ and from 32.15 to 56.45 ㎸/cm, respectively, according to the change from 40/60 to 0/100 in Zr/Ti concentration ratio. Fatigue and retention properties also improve much as the Zr/Ti concentration ratio change from 40/60 to 0/100. After applying 10$^{9}$ square pulses with $\pm$5V, the remanent polarization of the PLZT (10/40/60) thin film decreases 50％ from the initial state while that of the PLZT (10/0/100) thin film decreases 30％. In the results of retention measurements of 10$^{5}$ s, the remanent polarization of the PLZT (10/0/100) thin film decreases only 11％ from the initial state, while that of the PLZT (10/40/60) thin film decreases 40%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.609-615
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• 2005

The effects of Zr/Ti concentration ratio in PLZT (10/y/z) thin films prepared by sol-gel method are investigated for the NVFRAM application. As Ti amount of Zr/Ti concentration ratio increases, the dielectric constants at 10 kHz decrease from 550 to 400, while the loss tangents increase from 0.028 to 0.053 and the leakage current densities at 170 kV/cm decrease from $1.64\times10^{-6}$ to $1.26\times10^{-7}\;A/cm^2$. In the results of hysteresis loops measured at $\pm170kV/cm$, the remanent polarization and the coercive field increase from 6.62 to $12.86{\mu}C/cm^2$ and from 32.15 to 56.45 kV/cm, respectively, according to the change from 40/60 to 0/100 in Zr/Ti concentration ratio. Fatigue and retention properties also improve much as the Zr/Ti concentration ratio change from 40/60 to 0/100. After applying $10^9$ square pulses with $\pm5V$, the remanent polarization of the PLZT (10/40/60) thin film decreases $50\%$ from the initial state while that of the PLZT (10/0/100) thin film decreases $28\%$. In the results of retention measurements of 10s s, the remanent polarization of the PLZT (10/0/100) thin film dec.eases only $10\%$ from the initial state, while that of the PLZT (10/40/60) thin film decreases $40\%$.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.28-33
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• 2008

Lanthanum modified lead zirconate titanate ($Pb_{1.1}La_{0.08}Zr_{0.65}Ti_{0.35}O_3$) thin films were fabricated on indium doped tin oxide (ITO)-coated glass substrate by R.F magnetron sputtering method. The thin films were deposited at $500^{\circ}C$ and post-annealed with various temperature ($550-750^{\circ}C$) by rapid thermal annealing technique. The structure and morphology of the films were characterized with X-ray diffraction (XRD) and atomic force microscopy (AFM) respectively. The hysteresis loops and fatigue properties of thin films were measured by precision material analyzer. As the annealing temperature was increased, the remnant polarization value was increased from $10.6{\mu}C/cm^2$ to $31.4{\mu}C/cm^2$, and coercive field was reduced from 79.9 kV/cm to 60.9 kV/cm. As a result of polarization endurance analysis, the remnant polarization of PLZT thin films annealed at $700^{\circ}C$ was decreased 15% after $10^9$ switching cycles using 1MHz square wave form at ${\pm}5V$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1281-1284
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• 2005

In the micro electrochemical machining (ECM), unfavorable oxide/passive layer formation and overall corrosion of electrodes must be prevented. Generally, the stainless steel electrode corrodes, passivates or dissolves in the electrochemical cell according to the electrode potential. Therefore, the electrode must maintain stable potential. The stable electrode potentials of tool and workpiece were determined with the potentiodynamic polarization test and verified experimentally from the point of machining stability and machined surface quality.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.146-152
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• 2006

In micro electrochemical machining (ECM), electrodes should be prevented from unfavorable oxide and Passive layer formation on the machined surface or overall corrosion of the entire surface. Generally, metal electrodes corrode, passivate or dissolve in the electrochemical cell according to the electrode potential. Therefore, each electrode must maintain its stable potential. Tn this paper, the stable electrode potentials of tool and workpiece were determined using the potentiodynamic polarization test and verified experimentally considering machining stability and surface quality. Stable workpiece electrode potentials of two different passive materials of 304 stainless steel and nickel were determined in the 0.1 M sulfuric acid. Experimental results show good machined surface and fast machining rate using the determined electrode potentials.

• Electrical & Electronic Materials
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• v.2 no.2
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• pp.117-126
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• 1989

9/65/35 PLZT 세라믹을 그레인 크기에 따라 2단소성법으로 제조하여 그 전기적, 광학적특성을 관찰하고 횡모드 복굴절방식의 반사형 디스플레이소자를 제작하여 그 동작특성을 조사하였다. P-E곡선은 슬림형의 히스테리시스를 타나냈으며 그레인이 커질수록 유기분극과 광투과율은 증가하지만 복굴절율은 감소하여 디스플레이소자 구동시 콘트라스트 비가 감소 하였다. 디스플레이소자의 동작개시 전압은 1mm전극 간격에서 300V이고, $V_{(CR.Max)}$ 전압은 550V였으며 가시각도에 따른 콘트라스트 비의 비율((60.deg./90.deg.), $G_{S}$:4.mu.m)은 0.67이었다.다.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.366-367
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• 2018

본 논문은 태양광발전 시스템에서 태양광 모듈의 출력 저하 특성을 야기하는 PID (Potential Induced Degradation) 현상의 발생원인 및 출력회복을 위한 PID 저감 기법을 연구하였다. 태양광 모듈의 프레임과 셀 간에 발생하는 전위차로 인한 PID 현상의 직접적인 원인인 분극현상에 대해 분석하였으며, PID 현상이 태양광 모듈의 출력특성에 미치는 영향을 I-V 특성곡선 변화를 통해 해석하였다. PID 현상의 발생 원인을 기반으로 태양광 모듈의 전극 출력단인 양극과 음극을 단락시키고 접지된 프레임을 기준으로 양의 전압을 인가함으로써 태양광모듈의 출력특성을 회복하는 PID 저감 기법을 제안하였다.

• Journal of the Korean Ceramic Society
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• v.38 no.5
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• pp.474-478
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• 2001

유기 화학 기상 증착법(MOCVD)을 이용하여 반응기체 $O_2$의 양 및 Y와 Mn의 운반기체 비(Y/Mn)를 변화시켜가며 Si(100) 기판 위에서 MFSFET(metal-ferroelectric-semiconductor field effect transistor) 구조의 YMnO$_3$박막을 증착하였다. 반응기체 $O_2$의 양이 150sccm일 때 Y/Mn=2와 3인 경우 단일상의 육방정계 YMnO$_3$박막이 형성되었다. YMnO$_3$박막의 전기적 특성은 사방정계 YMnO$_3$박막에서는 나타나지 않았으나, 육방정계 YMnO$_3$박막의 경우 결정립 크기에 영향을 받아 단일상의 육방정계 YMnO$_3$박막 중 결정립 크기가 150nm~200nm(Y/Mn=2)인 경우에는 잔류분극이 100nC/$ extrm{cm}^2$인 P-E 이력곡선의 특성을 나타내었다.

• Korean Journal of Materials Research
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• v.7 no.5
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• pp.381-385
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• 1997

PEMOCVD에 의해서 SrBi$_{2}$Ta$_{2}$O$_{9}$밥막이 낮은 온도에서 성공적으로 Pt/Ti/SiO$_{2}$Si위에 증착되었다. 5$50^{\circ}C$에서 증착된 200nm박막은 치밀하고 작은 결정립을 보였으며 3V의 인가전압하에서 이력곡선은 포화되기 시작하였다. 3V에서 박막은 잔류분극 (P$_{r}$)과 항전계(E$_{c}$)는 각각 15$\mu$/$\textrm{cm}^2$과 50kV/cm이었다. 6V bipolar square pulse의 피로측정에서 박막은 1.0x$10^{11}$cycles까지 피로 현상을 보이지 않았다. PEMOCVD에 의해서 5$50^{\circ}C$에서 증착된 SBT박막은 비휘발성 기억소자에 충분히 활용할 수 있다.다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.585-588
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• 2005

The dissolution characteristic of metal shows the different tendency according to the applied electrical potential, the kind of electrolyte and pH value, etc. In the micro electrochemical machining (ECM), unfavorable oxide/passive layer formation and overall corrosion of electrodes must be prevented. The anodic polarization curve of nickel has distinct three dissolution regions, i.e. two active regions and the transpassive dissolution region. In this paper, the stable electrode potentials of workpiece and tool were determined in sulfuric acid and hydrochloric acid solution, respectively. In each solution, different machining property was shown and possible electrochemical reactions were discussed. On the basis of this experiment, the methodology to obtain the proper electrode potential was suggested.