• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.320-321
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• 2008

Ferroelectric $SrBi_2Ta_2O_9$(SBT) ceramics were deposite on Pt/Ti/SiO2/Si substrates using a sintered SBT target and then were annealed in the oxygen atmosphere at $750^{\circ}C$, the most excellent characteristics were shown, and the remnant polarization ($2P_r$) value and the coercive electric field ($E_c$) were respectively about 12.40[${\mu}C/cm^2$] and 30[kV/cm]. Moreover, the excellent fatigue characteristic t was little aged even after $10^{10}$ cycles of switchings. The leakage current density and the dielectric constant of the SBT capacitor annealed in the oxygen atmosphere were respectively approximately $2.13\times10^{-9}$ [A/$cm^2$] and 340.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.116-119
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• 2000

The a-axis and c-axis prefer oriented SBT thin films could be deposited on Pt(111)/Ti/$SiO_2$$650^{\circ}C$). The c-axis preferred orientation of SBT film can be obtained by Sr deficiency and high compressive stress. However, the a-axis-oriented grains can be formed under stoichiometric Sr content and nearly stress-free state.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.110-115
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• 2000

$SrBi_2Ta_2O_9$ thin films were deposited at room temperature on the usual (111) oriented Pt bottom electrodes using r.f. magnetron sputtering, and then post-annealed at 650-$800^{\circ}C$ for 30min in oxygen flow. Low temperature processing which shows the preferred oriented SBT thin films was obtained by controlling the sputtering pressure and/or Sr content in target. The orientation and grain growth behavior of SBT thin films were dependent on Sr contents in films. With increasing the excess Bi content up to 50% in SBT thin films, it was possible to lower the onset temperature of grain growth. The c-axis preferred oriented SBT thin films were well-grown under the condition of low post-annealing($650^{\circ}C$) by lowering post-annealing pressure. After $10^{11}$ switching cycles, no polarization degradation was observed in both preferred oriented SBT capacitors.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.401-405
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• 2004

Undoped SrB $i_2$T $a_2$O$_{9}$, donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ and acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99$ ceramics were prepared and their microstructure, ferroelectric P-E hysteresis and Curie temperature were investigated. Grain size did not influence P-E hysteresis curve in undoped SrB $i_2$T $a_2$O$_{9}$ ceramics. Donor-Doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics showed more saturated P-E hysteresis curve with larger remanent polarization (P$_{r}$) than undoped SrB $i_2$T $a_2$O$_{9}$ ceramics while acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99}$ ceramics led to a pinched P-E hysteresis loop. Larger polarization in donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics resulted from easier domain wall motion by Sr-vacancies.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.219-223
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• 2000

The ferroelectric SBT films were deposited on Pt/Ti/SiO$_2$/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)$_5$(dmae)]$_2$and Bi(C$_6$ 6/H$_5$)$_3$. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 40$0^{\circ}C$, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5~1.0, respectively. As-deposited film was amorphous. However, after annealing at 75$0^{\circ}C$ for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 75$0^{\circ}C$ were 4.7$\mu$C/$\textrm{cm}^2$ and 115.7kV/cm at an applied voltage of 5V, respectively. The SBT films annealed at 75$0^{\circ}C$ showed practically no polarization fatigue up to 10$^10$ switching cycles.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.20-23
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• 1999

본 연구에서는 $SrBi_xTa_2O_9$ 세라믹스에서 Bi 몰비 변화에 대한 x를 2.4, 2.6, 2.8, 3.0, 3.2로 변화시키면서 소결 온도도 변화하여 각각에 대한 구조 및 전기적 특성을 조사하였다. Bi 부족과 이상과잉에 따라 이상의 결정구조를 보였으며 소결온도가 높아질수록 Bi 휘발이 많아져 정방성이 떨어졌다. Sr/Bi/Ta=1/2.8/2 조성에서 가장 큰 정방성과 그레인 크기를 나타내었으며 그 조성에서 1000[$^{\circ}C$]로 소결한 시료에서 유전율 132를 보였고 1050[$^{\circ}C$]로 소결한 시료에서 잔류분극 1.134[${\mu}C/cm^2$]을 나타내었다.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.360-364
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• 2003

$Sr_{l}$ $\pm$x/$Bi_{2}$ $\pm$y/$Ta_2$ $O_{9}$ and $Sr_{l}$ $\pm$$Bi_{x}$ $2\pm$y$Nb_2$$O_{9}$ ceramics were prepared by a solid state reaction method. X-ray diffraction analysis indicated that single-phase of Bi-layered perovskite was obtained. According to Sr/Bi content ratio, Curie temperature( $T_{c}$), electromechanical factor($K_{p}$ ) and mechanical quality factor($Q_{m}$ ) were measured. The Curie temperature of SBN(SBT) rose from $414^{\circ}C$(314$^{\circ}C$) to $494^{\circ}C$(426$^{\circ}C$) when Sr/Bi content ratio was increased. In the case of Sr/Bi content ratio = 0.55/2.3, the maximum value of the mechanical quality factor $Q_{m}$ of SBT and SBN were obtained 3320 and 1010, respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.3
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• pp.213-225
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• 2002

Metal-Ferroelectric- Insulator- Silicon (MFIS) structured field effect transistor (FET) device was fabricated and characterized. Important issues to realize ferroelectric gate field effect transistor device were summarized in three sections. The choice of interlayer dielectric was made in the consideration of device functionality and chemical reaction between ferroelectric materials and silicon surface during fabrication process. Also, various ferroelectric thin film materials were taken into account to meet desired memory window and process compatibility. Finally, MFIS structured FET device was fabricated and important characteristics were discussed. For feasible integration of current device as random access memory array cell address schemes were also suggested.