• Title/Summary/Keyword: PZT Thin Film

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Fatigue Characteristics of PZT Thin Films Deposited by ECR-PECVD

  • Chung, Su-Ock;Lee, Won-Jong
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.4
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    • pp.177-185
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    • 2005
  • Fatigue characteristics of lead zirconate titanate (PZT) films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) were investigated. The fatigue characteristics were investigated with respect to PZT film thickness, domain structure, fatigue pulse height, temperature, electrode materials and electrode configurations. The used top and bottom electrode materials were Pt and $RuO_2$. In the fatigue characteristics with fatigue pulse height and PZT film thickness, the fatigue rates are independent of the applied fatigue pulse height at the electric field regions to saturate the P-E hysteresis and polarization $(P^*,\;P^A)$ characteristics. The unipolar and bipolar fatigue characteristics of PZT capacitors with four different electrode configurations $(Pt//Pt,\;Pt//RuO_2,\;RuO_2//Pt,\;and\;RuO_2//RuO_2)$ were also investigated. The polarization-shifts during the unipolar fatigue and the temperature dependence of fatigue rate suggest that the migration of charged defects should not be expected in our CVD-PZT films. It seems that the polarization degradations are attributed to the formation of charged defects only at the Pt/PZT interface during the domain switching. The charged defects pin the domain wall at the vicinity of Pt/PZT interface. When the top and bottom electrode configurations are of asymmetric $(Pt//RuO_2,\;RuO_2//Pt)$, the internal fields can be generated by the difference of charged defect densities between top and bottom interfaces.

Control of Grain Size of PZT Thin Film through Seed Layers (Seed Layer를 통한 PZT 박막의 결정립 크기 조절)

  • Kim, Tae-Ho;Kim, Ji-Young;Lee, In-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.273-278
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    • 2000
  • In order to study effects of interface layers between PZT films and electrodes for MFM(Metal-Ferroelectric-Metal) structure capacitors, we have fabricated the capacitors with the Pt/PZT/interface-layer/Pt/$TiO_2/SiO_2/Si$ structure. $PT(PbTiO_3)$ interface layers were formed by sol-gel deposition and PbO, $ZrO_2$ and $TiO_2$ thin layers were deposited by reactive sputtering. $TiO_2$ interface layers result in the finest grains of PZT films compared to $PbO_2$ and $ZrO_2$ layers. On the other hand, PT interface layers result in improved morphology of PZT films and do not significantly change ferroelectric properties. It is also observed that seed layers at the middle and top of PZT films do not give significant effects on grain size but the PT seed layer at the interface between the bottom electrode and the PZT films results in the small grain size.

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Fabrication and Electro-Mechanical Characteristic Analysis of Piezoelectric Micro-transformers (마이크로 압전변압기 제작 및 전기-기계적 특성 분석)

  • Kim, Seong-Kon;Seo, Young-Ho;Whang, Kyung-Hyun;Choi, Doo-Sun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.3
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    • pp.231-234
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    • 2008
  • For the applications which need a micro-power supply such as thin and flat displays, micro-robot, and micro-system, it is especially necessary to integrate the passive components because they typically need more than 2/3 of the space of the conventional circuit. Therefore, we have designed and fabricated a novel piezoelectric micro transformer using the PZT thin film and MEMS technologies for application to the energy supply device of the micro-systems. The dimensions of the micro-transformer is $1000{\mu}m\;{\times}\;400{\mu}m\;{\times}\;4.8{\mu}m$ $(length{\times}width{\times}thickness)$. The dynamic displacement of around $9.2{\pm}0.064{\mu}m$ was observed at 10 V. The dynamic displacement varied almost linearly with applied voltage. The average voltage gain (step-up ratio) was approximately 2.13 at the resonant frequency $(F_r=8.006KHz)$ and load resistance $(R_L)$ of 1 $M{\Omega}$.

Design, Fabrication and Characterization of Lateral PZT actuator using Stiffness Control (강성제어 구조물을 이용한 수평구동형 박막 PZT 엑츄에이터의 설계, 제작 및 특성평가)

  • 서영호;최두선;이준형;이택민;제태진;황경현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.756-759
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    • 2004
  • We present a piezoelectric actuator using stiffness control and stroke amplification mechanism in order to make large lateral displacement. In this work, we suggest stiffness control approach that generates lateral displacement by increasing the vertical stiffness and reducing the lateral stiffness using additional structure. In addition, an additional structure of a serpentine spring amplifies the lateral displacement like leverage structure. The suggested lateral PZT actuator (bellows actuator) consists of serpentine spring and PZT/electrode layer which is located at the edge of the serpentine spring. The edge of the serpentine spring prevents the vertical motion of PZT layer, while the other edge of the serpentine spring makes stroke amplification like leverage structure. We have determined dimensions of the bellows actuator using ANSYS simulation. Length, width and thickness of PZT layer are 135$\mu$m, 20$\mu$m and 0.4$\mu$m, respectively. Dimensions of the silicon serpentine spring are thickness of 25$\mu$m, length of 300$\mu$m, and width of 5$\mu$m. The bellows actuator has been fabricated by SOI wafer with 25$\mu$m-top silicon and 1$\mu$m-buried oxide layer. The bellows actuator shows the maximum 3.93$\pm$0.2$\mu$m lateral displacement at 16V with 1Hz sinusoidal voltage input. In the frequency response test, the fabricated bellows actuator showed consistent displacement from 1Hz to 1kHz at 10V. From experimental study, we found the bellows actuator using thin film PZT and silicon serpentine spring generated mainly laterally displacement not vertical displacement at 16V, and serpentine spring played role of stroke amplification.

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Densification and Electrical Properties of Screen-printed PZT Thick Films (스크린 프린팅법으로 제작한 PZT 후막의 치밀화와 전기적 특성)

  • Park, Sang-Man;Lee, Sung-Gap
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.7
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    • pp.667-672
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    • 2006
  • Ferroelectric $Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT(52/48)) thick films were fabricated by the screen-Printing method on the alumina substrates, and $PbTiO_3$ (PT) Precursor solution, which prepared by sol-gel method, was spin-coated on the PZT(52/48) thick films to obtain a densification. Its structural and electrical properties of the PZT(52/48) thick films with the treatment of PT precursor solution coating were investigated. The particle size of the thick films was increased with increasing the number of coatings and the thickness of the PZT-6 (6: number of coatings) films was about $60{\mu}m$. The relative dielectric constant increased and the dielectric loss decreased with increasing the number of PT sol coatings. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 475 and 2 %, respectively. The remanent polarization, coercive field and breakdown strength of the PZT-6 film were $32.6{\mu}C/cm^2$, 15 kV/cm and 60 kV/cm, respectively.

Polarized Raman Scattering Study of Highly(111)-oriented PZT Films in the Rhombohedral-Phase Field

  • 이현정;박정환;장현명
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.174-174
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    • 2003
  • Highly (111)-oriented PZT [Pb(Zrl-xTix)O3] thin films in the Zr-rich rhombohedral phase-field were successfully fabricated on Pt(111)/Ti/SiO2/Si substrates by combining PLD method with sol-gel process. These highly (111)-oriented films can be used as model systems for polarized Raman scattering study of PZT in the rhombohedral-Phase field because the (111)-direction is the principal off-center axis of the rhombohedral ferroelectricity. For this purpose, we have fabricated PZT films employing two distinctive compositions : one with Zr/Ti = 90/10 (abbreviated as PZT90/10) and the other with Zr/Ti= 60/40 (PZT60/40). The PZT90/10 film belongs to the octahedrally distorted FR(LT) phase with a cell-doubled structure, whereas the PZT60/40 is in the high-temperature FR(HT) phase-field at room temperature. To clearly separate E(TO) phonon modes from Al(TO) modes of the (111)-oriented rhombohedral film, we have suitably devised Z(X,Y)Z and Z(X,X)Z backscattering geometries for E(TO) and Al (TO), respectively. The polarized scattering experiment demonstrated that both types of (111)-oriented rhombohedral films closely followed the Raman selection rule.

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Electrical Characteristics of PZT Ferroelectric Thin Films (PZT 강유전 박막의 전기적 특성)

  • Kim, Hyun-Gwon;Paik, Dong-Soo;Choi, Hyung-Wook;Kim, Jun-Han;Park, Chang-Yup
    • Proceedings of the KIEE Conference
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    • 1993.11a
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    • pp.225-227
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    • 1993
  • Pb(Zr, Ti)$O_3$ ferroelectric thin layers were deposited onto Pt/$SiO_2$/Si substrates by Sol-Gel processing and annealed by RTA at $600^{\circ}C$ for $20{\sim}30\;sec$. microstructure of the films was examined by XRD and SEM analysis. Electrical properties of PZT thin films with different Zr/Ti ratio yield $P_r$ ranging $10{\sim}21{\mu}C/cm^2$, $E_c$, ranging $37.5{\sim}137.5\;kV/cm$, switching times faster than 180nsec, and leakage current about $20{\mu}A/cm^2$. The film was endured about $10^{10}$ fatigue cycles.

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Studies on Formation of Piezoelectric Film for Sensor and its Characteristic Estimation (센서용 piezoelectric film의 형성 및 특성 평가에 대한 연구)

  • Lee, Sung-Jun;Kim, Chul-Ju
    • Proceedings of the KIEE Conference
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    • 1998.07g
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    • pp.2509-2511
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    • 1998
  • In this study, we formed the piezoelectric film and estimated its characteristics for sensor application. The $Pb(Zr,Ti)O_3(PZT)$ was chosen as piezoelectric material and we used Sol-Gel method to form film. To increase film thickness, the multiple coatings were performed, and the good characteristics obtained in thick film compared to thin film. Because PZT film showed fine etching property as well as other good characteristics, it was thought that it was appropriate material for sensor fabrication.

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Effect of $Y^{3+}$ Impurity Addition on the Structural and Electrical Properties of PZT (65/35) Thin Film ($Y^{3+}$ 불순물 첨가가 PZT (65/35) 박막의 구조적, 전기적 특성에 미치는 영향)

  • 이규선;김준한;윤현상;이두희;박창엽
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.11a
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    • pp.24-27
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    • 1994
  • Variations with structural and electrical properties of Yttrium added PZT thin films were observed and measured respectively. Area of rosette was increased by Yttrium added and shapes of hysteresis curves were changed to slim type. $Y^{3+}$ ion substituted $Pb^{2+}$ ion and played the role of doner. Because the creation of space charges was restricted by Yttrium, degradation of remanent polarizations by cumutation of polarization reversals of PZT was protected. But coercive field was increased because of vacancies generated Yttrium added.