• The Korean Journal of Ceramics
• /
• 제6권2호
• /
• pp.110-115
• /
• 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.

• 한국재료학회지
• /
• 제13권6호
• /
• pp.360-364
• /
• 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.

• The Korean Journal of Ceramics
• /
• 제6권2호
• /
• pp.116-119
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.320-321
• /
• 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
• /
• 제6권3호
• /
• pp.219-223
• /
• 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 전문대학교육위원 P
• /
• pp.20-23
• /
• 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.