• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1301-1302
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• 2007

The multilayered $Pb_{1.1}(Zr_{0.4}Ti_{0.6})O_{3}$/$Pb_{1.1}(Zr_{0.6}Ti_{0.4})O_{3}/Pb_{1.1}(Zr_{0.4}Ti_{0.6})O_{3}$[PZT(4060)/(6040)/(4060)] thin films were deposited by RF sputtering method on the Pt/TiO2/SiO2/Si substrate. We investigated the effects of deposition conditions on the structural and electrical properties of the multilayered PZT thin films. All the multilayered PZT thin films showed dense and homogeneous structure without the presence of the rosette structure. The dielectric properties such as dielectric constant, loss, remanent polarization of the multilayered PZT thin film were superior to those of single composition PZT(4060) and PZT(6040) films, and those values for the multilayered PZT(10/20/10) thin film were 903, 1.01% and $25.60{\mu}C/cm^2$. This study suggests that the design of the multilayered PZT thin films capacitor with tetragonal and rhombohedral phase should be an effective method to enhance the dielectric and ferroelectric performance in devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.339-339
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• 2010

The metallic nanoparticles (Pt, Au, Ag. Cu, etc.) supported on ceria-titania mixed oxide exhibit a high catalytic activity for the water gas shift reaction ($H_2O\;+\;CO\;{\leftrightarrow}\;H_2\;+\;CO_2$) and the CO oxidation ($O_2\;+\;2CO\;{\leftrightarrow}\;2CO_2$). It has been speculated that the high catalytic activity is related to the easy exchange of the oxidation states of ceria ($Ce^{3+}$ and $Ce^{4+}$) on titania, but very little is known about the ceria titanium interaction, the growth mode of metal on ceria titania complex, and the reaction mechanism. In this work, the growth of $CeO_x$ and Au/$CeO_x$ on rutile $TiO_2$(110) have been investigated by Scanning Tunneling Microscopy (STM), Photoelectron Spectroscopy (PES), and DFT calculation. In the $CeO_x/TiO_2$(110) systems, the titania substrate imposes on the ceria nanoparticles non-typical coordination modes, favoring a $Ce^{3+}$ oxidation state and enhancing their chemical activity. The deposition of metal on a $CeO_x/TiO_2$(110) substrate generates much smaller nanoparticles with an extremely high activity. We proposed a mechanism that there is a strong coupling of the chemical properties of the admetal and the mixed-metal oxide: The adsorption and dissociation of water probably take place on the oxide, CO adsorbs on the admetal nanoparticles, and all subsequent reaction steps occur at the oxide-admetal interface.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.866-870
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• 1998

PLZT thin films were fabricated with different Zr/Ti ratios by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO$_2$/Si substrate. This PLZT thin films of 5000$\AA$ thickness were crystallized at $600^{\circ}C$, $O_2$ pressure 200m Torr. 2/55/45 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$\ulcorner=1550 and dielectric loss was 0.03 at 10kHz. At 2/70/30 PLZT thin film, coercive field and remnant polarization was respectively 19[kV/cm], 8[$\mu$C/$\textrm{cm}^2$]. Raman spectroscopy results showed that the bands of spectra became broader as the amount of Zr mol% increased and two crystal phase coexisted at 2/55/45 PLZT film. Raman spectroscopy was useful for crystal structure analysis of PLZT thin films.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.115-116
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• 2006

Dielectric PST (20/80) / PST (80/20) heterolayered thin films structures were created by a consequent deposition of the PST (20/80) and PST (80/20) thin films on the $Pt/Ti/SiO_2/Si$ substrate using alkoxide-based sol-gel method. Both structural and dielectric properties of heterolayered PST thin films were investigated for the tunable microwave device applications. As the number of coating increases, the lattice distortion decreased. It can be assumed that the lower PST layer affects a nucleation site or a seeding layer for the formation of the upper PST layer. The dielectric constant, dielectric loss and tunability of the PST-6 heterolayered structure measured at 100 kHz were 399, 0.022 and 57.9%, respectively. All these parameters showed an increase with increasing number of coatings due to the decrease in lattice distortion.

• 한국전기전자재료학회논문지
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• 제16권7호
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• pp.599-603
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• 2003

Ferroelectric B $i_4$$_{-x}$N $d_{x}$ $Ti_3$ $O_{12}$ (BNdT) thin films with the composition(x=0.75) were prepared on Pt/Ti/ $SiO_2$(100) substrate by metal-organic deposition. The films were annealed by various temperatures from 550 to $650^{\circ}C$ and then the electrical and structural characteristics of BNdT films were investigated for the application of FRAM. Electrical properties such as dielectric constant, 2Pr and capacitance were quite dependent on the thermal heat treatment. The measured 2Pr value on the BNdT capacitor annealed at $650^{\circ}C$ was 56$\mu$C/$\textrm{cm}^2$ at an applied voltage of 5V. In fatigue characteristics value remained constant up to 8$\times$10$^{10}$ read/write switching cycles at a frequency of 1Mhz regardless of annealing temperatures.

• 센서학회지
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• 제15권6호
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• pp.406-410
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• 2006

The films of indium oxide $In_{2}O_{3}$) were deposited onto $SiO_{2}$ coated Si wafers by a thermal evaporation method. Substrate temperature was varied from $25^{\circ}C$ to $300^{\circ}C$. Deposition rate increased to $250^{\circ}C$ and then decreased rapidly. The crystallographic properties and surface morphologies of the films were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The films deposited at $250^{\circ}C$ were found to have a nanobelt structure. Resistor-type gas-sensors were fabricated with $In_{2}O_{3}$ films using Pt as electrodes. The resistance variation of $In_{2}O_{3}$ films with the concentration of NO gas was measured. The $In_{2}O_{3}$ films deposited at $250^{\circ}C$ showed the highest sensitivity to the NO gas.

• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.361-364
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• 2003

It was investigated that the structural and electrical Properties of Ce-doped Ba(Zr$_{x}$Ti$_{1-x}$ )O$_3$ (BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/SiO$_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/O$_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 nm (RMS at 500 $^{\circ}C$, Ar:6 sccm, $O_2$:6 sccm). It was found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• 한국세라믹학회지
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• 제35권9호
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• pp.945-952
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• 1998

Ferroelectric Sr0.8Bi2.4Ta2O9 stock solutions were prepared by MOD(Metaloganic Decompostion) process. The phase transformation for the layered perovskite of the SBT thin films by changing RTA(Rapid her-mal Annealing) temperatuer from 700$^{\circ}C$to 780$^{\circ}C$ were observed using XRD and SEM. Layered perovskite phase began to appear above 740$^{\circ}C$ and then SBT thin films were annealed at 800$^{\circ}C$ for 1hr for its com-plete crystallization. The specimens showed well shaped hysteresis curves without post annealing that car-ried out after deposition of Pt top electrode. The SBT thin films showed the asymmetric ferroelectric pro-perties. It was confirmed that the properties were caused by interface effect to SBT and electrode by leak-age current density measurement and asymmetric properties reduced by post annealing. At post annealing temperature of 800$^{\circ}C$ remanant polarization values (2Pr) were 6.7 9 ${\mu}$C/cm2 and those of leakage current densities were 3.73${\times}$10-7 1.32${\times}$10-6 A/cm2 at 3, 5V respectively. Also bismuth bonding types of SBT thin film surface were observed by XPS.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.301-304
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• 2002

We investigated the structural and electrical properties of Ce-doped Ba($Zr_{0.2}Ti_{0.8}$)$O_3$(BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/$SiO_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/$O_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 m (RMS at $500^{\circ}C$, Ar:6 scrim, $O_2$:6 sccm). We have found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.197-197
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• 2010

Pb(Zr,Ti)O3/BiFeO3/(PZT/BFO) multilayer thin films were coated on Pt/Ti/SiO2/Si substrates by chemical solution deposition. With increasing the annealing temperature, the dielectric and leakage current density properties of multilayered PZT/BFO/PZT thin films were improved. The current density of the PZT/BFO/PZT filmannealing at $600^{\circ}C$ was about 189.39(x10-9A/cm2) at 10V. The relative dielectric constant and the dielectric loss of the PZT/BFO/PZT thin film annealing at $600^{\circ}C$ were about 318 and 0.161%, respectively.