• Journal of Magnetics
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• v.13 no.2
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• pp.61-64
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• 2008

We studied the effect of the variation of the lattice constant on the electrical properties of $SrRuO_3$ thin films. In order to obtain films with different volumes, we varied the substrate temperature and oxygen pressure during the growth of the films on $SrTiO_3$ (001) substrates. The films were grown using a pulsed laser deposition method. The X-ray diffraction patterns of the grown films at low temperature and low oxygen pressure indicated the elongation of the c-axis lattice constant compared to that of the films grown at a higher temperature and higher oxygen pressure. The in-plane strain states are maintained for all of the films, implying the expansion of the unit-cell volume by the oxygen vacancies. The variation of the electrical resistance reflects the temperature dependence of the resistivity of the metal, with a ferromagnetic transition temperature inferred form the cusp of the curve being observed in the range from 110 K to 150 K. As the c-axis lattice constant decreases, the transition temperature linearly increases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.231-237
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• 2001

Etch rates up to 120 nm/min for $Ta_{2}O_{5}$ were achieved in both $SF_{6}/Ar$ and $Cl_{2}/Ar$ discharges. The effect of ultraviolet (UV) light illumination during ICP etching on $Ta_{2}O_{5}$ etch rate in those plasma chemistries was examined and UV illumination was found to produce significant enhancements in $Ta_{2}O_{5}$ etch rates most likely due to photoassisted desorption of the etch products. The effects of ion flux, ion energy, and plasma composition on (Ba, Sr)$TiO_3$ etch rate were examined and maximum etch rate ~90 nm/min was achieved in $Cl_{2}/Ar$ ICP discharges while $CH_{4}/H_{2}/Ar$ chemistry produced extremely low etch rates (${\leq}10\;nm/min$) under all conditions.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.202-208
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• 1997

Bi-layered SrBi2Ta2O9(SBT) films were deposited on Pt/Ti/SiO2/Si sibstrates by rf magnetron sputt-ering at room temperature and then were annealed at 75$0^{\circ}C$, 80$0^{\circ}C$ and 85$0^{\circ}C$ for 1 hour in oxygen at-mosphere. The film composition of SrBi2Ta2O9 was obtained after depositing at room temperature and annealing at 80$0^{\circ}C$. Excess 20mole% Bi2O3 and 30 mole% SrCO3 were added to the target to compensate for the lack of Bi and Sr in SBT film. 200 nm thick SBT film exhibited and dense microstructure, adielectric constant of 210, and a dissipation factor of 0.05 at 1 MHz frequency. The films exhibited Curie temperature of 32$0^{\circ}C$ and a dielectric constant of 314 at that temperature under 100 kHz frequency. The remanent polarization(2Pr) and the coercive field(2Ec) of the SBT films were 9.1 $\mu$C/$\textrm{cm}^2$ and 85 kV/cm at an applied voltage of 3V, resspectively and the SBT film showed a fatigue-free characteristics up to 1010 cy-cles under 5V bipolar pulse. The leakage current density of the SBT film was about 7$\times$10-7A/$\textrm{cm}^2$ at 150 kV/cm. Fatigue-free SBT films prepared by rf magnetron sputtering can be suitable for application to non-volatile memory device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.685-688
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• 2003

[ $(Ba,Sr,Ca)TiO_3$ ] powders, prepared by the sol-gel method, were mixed with an organic vehicle and the BSCT thick films were fabricated by the screen printing techniques on alumina substrates. The grain size decreased with increasing amounts of $MnO_2$, and the BSCT(50/40/10) thick film doped with 1wt% $MnO_2$ showed a value of 6.5mm. The thickness of thick films by four-cycle on printing/drying was approximately 100mm. The relative dielectric constant, dielectric loss and tunability of the BSCT(S0/40/10) thick films doped with 1.0wt% $MnO_2$ were 1296, 0.61% and 11.18%, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.11
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• pp.526-530
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• 2002

The $(Sr_{0.9}Ca_{0.1})TiO_3(SCT)$ thin films were deposited on Pt-coated electrode (Pt/TiN/$SiO_2$/Si) using RF sputtering method. The composition of SCT thin film deposited on Si substrate at room temperature is close to stoichiometry(1.081 in A/B ratio). The maximum dielectric constant of SCT thin film was obtained by ammealing at $600^{\cric}C$. The temperature dependence of dielectric loss showed a value within 0.02 in temperature ranges of -80 ${\sim}$ +90$^{\circ}C$. The capacitance characteristics showed a stable value within ${\pm}$4%. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films was observed at the frequency above 200kHz.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.233-239
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• 2000

Sr0.9Bi2+xTa2O9(x=0, 0.1, 0.2, 0.3) thin films on IrO2/SiO2/Si or Pt/Ti/SiO2/Si substrate were prepared by spin coating method using SBT stock solutions synthesized by MOD process. SBT thin films on IrO2 transformed to layered perovskite phase at $700^{\circ}C$, but showed low breakdown voltage due to their porous microstructure. The smaple of Sr0.9Bi2+xTa2O9 composition showed the best dielectric and electrical properties. When the sample of the same composition was annealed at 80$0^{\circ}C$, the dielectric and electric properties were improved due to the grian growth and dense surface. the remanent polarization values(2Pr) at $\pm$3 V for IrO2 and Pt electrodes were 10.5, 7.15$\mu$C/$\textrm{cm}^2$, respectively. The SBT thin film with IrO2 electrode showed the lower coercive field. The leakage current density and breakdown voltage of SBT thin films on IrO2 were higher than those on Pt.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.104-104
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• 2003

RF magnetron sputtering 법을 이용하여 LaA1O$_3$, SrTiO$_3$, MgO 단결정 기판 위에 BaTiO$_3$ 박막을 에피텍셜하게 증착하여 박막의 특성과 마이크로 웨이브에서의 유전특성을 평가하였다. 각 기판위에 증착한 박막의 격자상수와 FWHM을 조사하였고, pole figure로 에피텍셜 성장을 관찰하였다. 각 시편에 상부 전극으로 interdigital 타입의 전극을 photolithography 하여 캐패시턴스와 tan $\delta$을 조사하였다. 각 기판의 변화에 따른 격자상수 변화와 유전 특성의 변화를 고찰하였다.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.116-121
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• 1999

0.5 wt%Nb-doped SrTiO3(Nb: STO) thin film was prepared on MgO(100) single crystal substrates by Pulsed Laser Deposition (PLD). The Crystallinity and the orientation of Nb:STO thin films were characterized by XRD with changing the thin film processing condition-oxygen partial pressure, substrate temperature, deposition time and the distance between target and substrate. The orientation of Nb:STO thin film showed (100), (110) and (111) orientations at the substrate temperature of $700^{\circ}C$. The lattice parameter of Nb:STO decreased with increasing Po2 and showed 0.3905 nm at Po2=100 Pa, which was similar to that of the bulk. The thickness of Nb:STO thin film increased with increasing the deposition time and with decreasing the distance between target and substrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.768-771
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• 2004

Pb0.5,Sr0.5TiO3(PST) thin films were deposited on Si with MgO (100) buffer layer by the alkoxide-based sol-gel method. Structural and dielectric properties of PST thin films for the tunable microwave device applications were investigated. For the MgO/Si buffer layer, the PST thin films exhibited highly (100) orientation. The MgO buffer layer affects the stress state of the (100)-oriented PST thin films. The dielectric constant, tunability, and FOM of the highly (100)-oriented PST thin film increased with increasing annealing temperature due to the decrease in lattice distortion. The differences in dielectric properties may be attributed to the change in the film stress. The dielectric constants, dielectric loss and tunability of the PST thin films deposited on the MgO/Si substrates measured at 10 kHz were 822, 0.025, and 80.1%, respectively.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.1-6
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• 2009

We report a successful fabrication of $high-J_c\;NdBa_2Cu_3O_{7-{\delta}}$ (NdBCO) films on $SrTiO_3$(STO) (100) substrates by pulsed laser deposition (PLD) in a relatively wide processing window. Under various oxygen pressures controlled by either 1%$O_2$/Ar mixture gas or pure $O_2$ gas, strongly c-axis oriented NdBCO films were grown at the substrate temperature $(T_s)\;of\;800^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas and also in 400 and 800 mTorr with pure $O_2$ gas. These samples exhibited $T_c$ values over 90K and $J_c$ values of $2.8-3.5MA/cm^2$ at 77K in self-field (77K, sf). On the other hand, $J_c$ values over $1A/cm^2$ were obtained at the temperature regions of $700-830^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas at those of $750-830^{\circ}C$ in 800 mTorr with pure $O_2$ gas. Unlike previous reports, resent results support that the PLD processing window for high-Jc NdBCO films is not narrow.