서지주요정보
졸겔 PLZT박막의 상형성과 강유전 및 광도파특성 = Phase formation, and ferroelectric and waveguiding characteristics of sol-gel PLZT thin films
서명 / 저자 졸겔 PLZT박막의 상형성과 강유전 및 광도파특성 = Phase formation, and ferroelectric and waveguiding characteristics of sol-gel PLZT thin films / 윤대성.
발행사항 [대전 : 한국과학기술원, 1996].
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8006950

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 96023

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초록정보

For structural and composition analysis, sol-gel lead lathanum zirconate titanate [PLZT(9/65/35)] thin films fabricated on ITO-coated Corning 7059 glasses were analyzed using a scanning electron microscope and a scanning Auger microscope. The PLZT film consisted of micron-scale spheroidal perovskite grains and nano-scale pyrochlore grains. The perovskite grains had higher lead(Pb), lower oxygen(O) and zirconium(Zr) contents than the pyrochlore grain. The Auger depth profile and SEM observation of the cross-sectional fracture surface showed higher perovskite content near the interface between PLZT and ITO films than the surface of the PLZT film. Effects of heating schedule on the crystallization kinetics of the amorphous PLZT thin films were also studied. Firing at higher heating rate increased the number of perovskite nuclei and decreased the pyrochlore content in the film. The highest value of perovskite content was over 95% at the sample which was inserted directly to a $600^oC$ furnace and heat-treated for 1 h. Epitaxial and highly preferred lead lathanum zirconia titanate [PLZT(9/50/50) and (10/0/100)] thin films were fabricated on various substrates using the sol-gel method. The films fabricated on $SrTiO_3$, r-plane sapphire, and Pt/Ti/MgO grew epitaxially to (100), (110) and (100) orientations, respectively. The aligned and the polycrystalline PLT(10/0/100) films had a dielectric constant of 738 and 540 at 1 kHz, respectively. The spontaneous polarization($P_s$) and the remanent polarization ($P_r$) and the coercive field($E_c$) of the aligned PLT(10/0/100) film were 51.2μC/㎠, 35.5μC/㎠, and 91.8 kV/cm, respectively. The $P_s$, the $P_r$, and the $E_c$ of the polycrystalline PLT film were 33.2μC/㎠, 18.2μC/㎠ and 124.2 kV/cm, respectively. In the fatigue test, the decay in $P^*-P\^$ after $10^8$ cycles was about 58 % and 92 % of the initial value for the aligned and the polycrystalline PLT(10/0/100) films. The aligned PLT thin films had a leakage current of $2.0×10^{-8}A/㎠$ whereas the polycrystalline films of $5×10^{-9} A/㎠$ at the electric field of 200 kV/cm. The epitaxial PLZT thin film had higher dielectric constant and leakage current, and better ferroelectricity and fatigue resistance than the polycrystalline films. The polarization switching characteristics of the epitaxial and the polycrystalline PLT thin films are studied using modified Sawyer-Tower circuit. The maximum switching current decreases as the applied pulse voltage decreases. In addition, the switching time of the epitaxial film becomes longer when the applied voltages smaller. The switching time of the film, however, became shorter as the delay time of the applied pulse increased. On the other hand, nonswitching characteristics of the film seems to be independent on the delay time of pulse. Compared with the as-grown sample, the fatigued film shows smaller maximum induced current and longer switching time. Waveguiding properties and propagation losses of the PLT films on Corning 7059 glass substrates were measured using the prism coupling method and the scattering detection method. Successful waveguiding was established in all the samples. A 7 cycle-coated film(0.7㎛) exhibited three guided modes of $TE_0$, $TE_1$ and $TE_2$. Effects of drying conditions on refractive indice and propagation losses of the films were investigated. As the drying temeprature of the film increases, the refractive index increases and the propagation loss decreases. The lowest value of the measured propagation losses was 3.3 dB/cm in the sample which was dried at $450^oC$ for 30 min and heat-treated at $550^oC$ for 30 min.

서지기타정보

서지기타정보
청구기호 {DMS 96023
형태사항 iv, 154 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Dae-Sung Yoon
지도교수의 한글표기 : 노광수
지도교수의 영문표기 : Kwang-Soo No
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 수록
주제 졸겔
납,란탄
지르코늄
티탄산 박막
상형성
강유전특성
광도파특성
Sol-gel
PLZT film
Phase formation
Ferroelectric property
Waveguiding property
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