• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.18-19
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• 2006

The bismuth zinc niobate(BZN) pyrochlore thin films were fabricated on Pt(111)/Ti/$SiO_2$/p-Si(100) substrates using a reactive rf magnetron sputtering method at the conditions of working gas ratio Ar:$O_2$=90:10, substrate temperate $R.T{\sim}600^{\circ}C$, rf power 50 W. The dielectric constant, tunability, leakage current density and crystallinity of thin films changed with a substrate temperate. The BZN pyrochlore thin films sputtered with a substrate temperature of $600^{\circ}C$ and RTA at $800^{\circ}C$ showed a leakage current density lower than $10^{-8}\;A/cm^2$ at the range of ${\pm}300\;kV/cm$.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.516-524
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• 1995

In this study, to prepare the dielectric (Ba, Sr)TiO3 thin films by the sol-gel process, Titaminum (IV) sio-propoxide (Ti[OCH(CH3)2]4), Ba and Sr acetate were used for sol and thin films were prepared by dip-coating process. Stability of sol decreased with the increase of Sr, and thickness of thin films were obtained 0.13~0.17${\mu}{\textrm}{m}$ by 1 coating cycle. Transmittance of amorphous thin films heated at 500 and 55$0^{\circ}C$ was very good, and crystallization tendency of thin films according to heat-treatment temperature and crystallization characteristics of thin films heated at 11$0^{\circ}C$ for 3 hrs were analysed. As a result, good perovskite structure was obtained higher than 100$0^{\circ}C$, and tetragonality of thin film was decreased but pyrochlore was formed with increasing Sr. In case of addition to substitute 0.4mol% Sr for Ba, dielectric constant was 288 and loss factor (tan $\delta$) was 0.04.

• Journal of the Korean Ceramic Society
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• v.35 no.11
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• pp.1130-1140
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• 1998

Thin films of $Bi_4Ti_3O_{12}\;nBaTiO_3(n=1&2)$ were prepared using sols erived Ba-Bi-Ti complex alkoxides. The sols were spin-cast onto $Pt/Ti/SiO_2/Si$ substrates and followed by pyrolysis for 1 hr at $620^{\circ}C,\;700^{\circ}C\;and\;750^{\circ}C$ In the thin films a pyrochlore phase seemed to be formed at a lower temperature and then tran-formed to the layered perovskite phase as the heating temperature increased. In the thin films pyrolyzed at formed to the layered perovskte phase as the heating temperature increased. In the films pyrolyzed at $750^{\circ}C$ the amount of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ reached to 94% while $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ was 77% in composition. This result shows that the formation of the layered pervoskite phase becomes difficult as the amount of complexing $BaTiO_3$ increases. The microstructures and the electrical properties of the thin films were gen-erally improved with the incease of the heating temperature. However the presence of the pyrochlore phase could not be removed effectively. Our study showed that the electrical properties of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ were pronouncedly improved with complexing with BaTiO3 when compared to those of $Bi_4Ti_3O_{12}$ while the presence of the pyrochlore phase was detrimental to the those of $Bi_4Ti_3O_{12}{\cdot}2BaTiO_3$.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.859-864
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• 1991

High quality lead titanate thin films were fabricated by spin coating on a silicon substrate. The resulting dried gel layers were uniform in thickness through 2$\times$2 $\textrm{cm}^2$ area, and polycrystalline perovskite structures developed almost crack free with a heat treatment above 50$0^{\circ}C$ in films with thickness above 360 nm. Metastable pyrochlore structures were observed in films with thickness of 160 nm when heat treated at 500 and $600^{\circ}C$, but these structure did not appear in films with thickness of 360 nm. The thickness dependence in crystal structure of films was studied. by varying the substrate condition and analyzing the interface between the film and substrate. In native oxide films on silicon stbstrates, amorphous dried gel layers were heterogeneously nucleated. Metastable cubic pyrochlore structure could be crystallized in amorphous native oxide.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.211-215
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• 2010

Pulsed laser deposition is a very efficient technique for fabricating thin films of complex compounds. In the present work, $Bi_2O_3$-MgO-ZnO-$Nb_2O_5$ (BMZN) pyrochlore thin films were deposited on platinized Si substrates at various temperatures by using pulsed laser deposition technique. These films have been characterized by X-ray diffractometer (XRD), atomic force microscopy (AFM) to investigate their structural, morphological properties. MIM structure was manufactured to analyze di-electrical properties of BMZN thin films. XRD results reveal the thin films deposited at less than $400^{\circ}C$ show only amorphous phase, the crystallized thin films was observed when the thin films were prepared temperature at above $500^{\circ}C$. From AFM, it was known that the thin film grown at $400^{\circ}C$ is the densest. Dielectric constant increased with increasing temperature up to $400^{\circ}C$ at 100 kHz and dramatically decreased at the higher temperature. A aspect of dissipation factor was the exact opposite of dielectric constant. BMZN thin films grown at $400^{\circ}C$ exhibited a high dielectric constant of 60.9, a low dissipation factor of 0.007 at 100 kHz.

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1101-1108
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• 1996

No-doped PZT thin films have been fabricated on Pt/Ti/SiO2/Si substrate using Sol-Gel technique. A fast annealing metho (three times of intermediate and final annealing) was used for the preparation of multi-coated 1800$\AA$ thick Nb-doped PZT thin films. As Nb doping percent was increased leakage current was lowered approximately 2 order but dielectic properties were degraded due to the appearance of pyrochlore phase and domain pinning. Futhermore the increase of the final annealing temperature up to 74$0^{\circ}C$lowered the pyrochlore phase content resulting in enhancing the dielectric properties of the Nb doped films. The 3%-Nb doped PZT thin films with 5% excess Pb showed a capacitance density of 24.04 fF/${\mu}{\textrm}{m}$2 a dielectric loss of 0.13 a switchable polarization of 15.84 $\mu$C/cm2 and a coercive field of 32.7 kV/cm respectively. The leakage current density of the film was as low as 1.47$\times$10-7 A/cm2 at the applied voltage of 1.5 V.

• Journal of Ceramic Processing Research
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• v.21 no.6
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• pp.725-730
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• 2020

This study investigated the structural and electrical properties of thin K(Ta_0.6Nb_0.4)O₃ films for their applicability to electrocaloric devices. Both of the sol-gel and spin coating methods were used to fabricate thin films. Those sintered at 650 ℃ showed a KTN phase with pyrochlore of K₂Ta₂O₆, but those sintered at 750 ℃ showed pure polycrystalline phase without a pyrochlore phase. The lattice constants observed were a= 3.990nm. The dielectric constant rapidly decreased due to decrease in polarization of space charge approximately at an applied frequency of 10 kHz. The dielectric constant and loss at 30 ℃ of the thin films sintered at 750 ℃ were 3,617 and 0.264. The dielectric constant of the specimen sintered at 750 ℃ decreased to about -8.27 %/V according to the applied DC field. The remanent polarization and coercive field at 36 ℃ of the specimen sintered at 750 ℃ were 20.0 µC/cm² and 122.6 kV/cm. When the electric field of 247 kV/cm was applied to the specimen sintered at 750 ℃, the highest electrocaloric property of 3.02 ℃ was obtained.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.21-25
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• 1998

We investigated the optical properties of lead zirconate($PbZrO_3$, PZ) thin films. The PZ films for the measurement of optical properties were prepared on ITO glass by sol-gel method. By post annealing, with annealing temperature $T=700^{\circ}C$, the pyrochlore phase of as-deposited specimen was transformed into the perovskite phase. The surface of films were plat, transmittance were from 60 to 80% at 480~2000nm, and refractive index were from 2.1 to 1.9 at 480~1000nm.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.530-536
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• 2000

During the grain growth of the PZT thin films by selective nucleation method using PZT seed, it was found that the grain size was saturated with the annealing temperature. The saturation of grain size was analyzed by the interfacial energy which appeared during the crystallization. The factors affecting the saturation of grain size were found to be the interfacial energy between perovskite phase and pyrochlore phase, and PZT thin film and the bottom Pt electrode. When the ion damage was introduced to the grain-size saturated PZT thin films, further lateral growth was observed. Pt bottom electrode thickness was changed to control the interfacial energy between the PZT thin film and the Pt bottom electrode. When Pt thickness was increased, the grain size was also increased, because the lattice parameter of Pt films was increased with the thickness of the Pt films. The incubation time of nucleation was increased with the amount of the ion damage on the Pt films.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.783-792
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• 1995

Sol-Gel derived ferroelectric PZT thin films were fabricated on ITO/Glass and Si/SiO2 substrates. In order to investigate the effect of catalysts on the densification and crystallization of PZT thin films, a nitric acid or ammonium hydroxide was added to the PZT stock solution at the state of partial hydrolysis reaction. The measured pH for a stable PZT sol was 5.2~9.3. In case of an acid-catalyzed PZT sol, a highly condensed particulate PZT sol was formed by accelerating the hydrolysis reaction. But weakly branched polymeric PZT sol was formed with a base-catalyzed condition. The difference in densification behavior was not found in the pH range of added catalyst, but the refractive index of PZT thin film was increased rapidly as the annealing temperature increased. The PZT thin film annealed at 54$0^{\circ}C$ for 10 min was fully densified and its refractive index was above 2.4. When the annealing temperature increased, the transition from the pyrochlore phase to perovskite appeared at 54$0^{\circ}C$. The base-catalyzed PZT thin film suppressed to form the pyrochlore phase and proceeded effectively to convert the perovskite phase. This was due to the formation of polymeric molecular structure by controlling the hydrolysis and condensation reaction through the additiion of the ammonium hydroxide.