• 한국세라믹학회지
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• 제35권9호
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• pp.1002-1005
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• 1998

Bismuth titanate thin films were prepared on {{{{ { SrTiO}_{3 } }}(100) and Si(100) substrates by dipping-pyrolysis pro-cess using metal naphthenates as starting materials. crystallinity and in-phase alignment of the films were analyzed by X-ray diffraction $\theta$-2$\theta$ scans and $\beta$ scans (pole-figures) respectively. Highly c-axis-oriented {{{{ { { {Bi }_{4 }Ti }_{3 }O }_{12 } }} thin films with smooth surfaces were obtained after heat treatment at 75$0^{\circ}C$ on {{{{ { SrTiO}_{3 } }}(100) sub-strate while the films grown of Si(100) exhibited polycrstalline characteristics. C-axis oriented film show-ed an epitaxial relationship with the {{{{ { SrTiO}_{3 } }} substrate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.180-182
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• 2004

Polycrystalline $BaTiO_3/SrTiO_3$ powder was prepared by sol-gel process and the multilayered thick films were prepared on the $Al_2O_3$ substrates by screen printing method. The films were sintered at $1400^{\circ}C$ for 2 hours in the air. The structural and dielectric properties were investigated, The X-ray diffraction (XRD) patterns indicate that the BST phase and porocity were formed in the interface of $BaTiO_3/SrTiO_3$ multilayered thick films. The dielectric constant and the dielectric loss of the BT/ST/BT/ST multilayered thick films were about 247 and 0.84% at 1MHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1488-1490
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• 2002

The (Bi,Ba,Sr)$TiO_3$[BBST] thin films were fabricated on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. We investigated the effects of Ar/$O_2$ rates on the structural properties of BBST thin films. Decreasing the $O_2$ rates, the intensity of $BaBi_4Ti_4O_{15}$ and $Bi_4Ti_3O_{12}$ peaks were increased but the $(Ba_{0.5}Sr_{0.5})TiO_3$ peak was decreased. In the case of BBST thin films deposited with condition of 90/10 (Ar/$O_2$) ratio, the composition of Ba/Sr/Bi was 0.35/0.4/0.25. Also, in the BBST thin films deposited with condition of 80/20(Ar/$O_2$) ratio, the composition of Br,Sr and Ti were relatively uniform. But the component of Bi and Ti were diffused into the Pt layers.

• 한국진공학회지
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• 제5권4호
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• pp.359-364
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• 1996

Pt/Ti/$SiO_2$/Si 기판 위에 r.f. 마그네트론 스퍼터링 방법으로 $300^{\circ}C$이하의 저온에서 SrTiO3 박막을 증착하였다. XRD, RBS, TEM, EPMA로 증착된 박막의 재료적 특성을 분석하였고, Al/$SrTiO_3$/Pt의 구조로 커패시터를 제작하여 전기적 특성을 분석하였다. 기판온도가 증가함에 따라 박막의 결정성과 유전율이 향상되었으나, $200^{\circ}C$이하의 기판온도에서는 Sr이 결핍된 조성을 갖게 되어 증착된 박막이 반도성을 나타내었다. 증착중에 기판에 양의 d.c. 전압을 10~30V 인가함으로써 박막의 결정성이 크게 향상되었고, 유전특성도 개선되었다. $300^{\circ}C$의 기판온도에서 20V의 d.c. bias를 인가하여 증착한 400nm 두께의 $SrTiO_3$ 박막은 <211> 우선방향성을 갖는 주상정 구조와 화학양론적인 조성을 나타내었고, 본 연구에서 가장 우수한 전기적 특성을 보였다. 100 kHz에서 유전율이 98, 유전손실이 3.4%였으며, 3V에서 누설전류는 $10^{-5}A/\textrm{cm}^2$였다.

• 한국세라믹학회지
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• 제45권6호
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• pp.358-362
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• 2008

$BiFeO_3$ films were hetero-epitaxially grown on $SrTiO_3$ substrate with a various orientation by pulse laser deposition. $BiFeO_3$ films grown on (111) $SrTiO_3$ substrate have a rhombohedral structure, identical to that of single crystals. On the other hand, films grown on (110) or (001) $SrTiO_3$ substrate are monoclinically distorted from the rhombohedral structure due to the epitaxial constraint. The easy axis of spontaneous polarization is close to [111] for the variously oriented films. Dramatically enhanced polarization and magnetization have been found for $BiFeO_3$ thin films grown on $SrTiO_3$ substrate comparing to that of $BiFeO_3$ crystals. The results are explained in terms of an epitaxially-induced transition between cycloidal and homogeneous spin states, via magneto-electric interactions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.73-76
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• 2001

We deposited epitaxial $Ba_{0.6}Sr_{0.4}TiO_{3}(BST)$ films having thickness of 400 nm on MgO(001) substrates, where a 10 nm thick $Ba_{1-x}Sr_{x}TiO_{3}$ (x = 0.1 - 0.7) interlayer was inserted between BST and MgO to manipulate the stress of the BST films. Since the main difference of those epitaxial BST films was the lattice constant of the interlayers, we were very successful in controlling the stress of the BST films. BST films under small tensile stress showed larger dielectric constant than that without stress as well as those under compressive stress. Stress relaxation was investigated using epitaxial BST films with various thicknesses grown on different interlayers. For BST films grown on $Ba_{0.7}Sr_{0.3}TiO_{3}$ interlayers, the critical thickness was about 600 nm. On the other hand, the critical thickness of single-layer BST film was less than 100 nm.

• 한국세라믹학회지
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• 제33권2호
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• pp.177-182
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• 1996

strontium titanate (SrTiO3) thin films deposited on Pt/MgO were prepared by Plasma Enhanced Metal Orgainc Chemical vapor Deposition (Pe-MOCVD). The crystallinity of SrTiO3 thin films increased with increasing depo-sition temperature and SrF2 second phase disappeared at 55$0^{\circ}C$ The films showed a dielectric constant of 177 and a dissipation factor of 0.0195 at 100 kHz. The variation of capacitance of the films with applied voltage was small showing paraelectric properties. The charge storage density and leakage current density were 40fC/${\mu}{\textrm}{m}$2 and 3.49$\times$10-7 A/cm2 at 0.25 MV/cm, respectively.

• 한국전기전자재료학회논문지
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• 제18권9호
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• pp.810-814
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• 2005

[ $Pb(Zr_{0.2}Ti_{0.8})O_3/SrRuO_3$ ] heteroepitaxial thin films were deposited at various temperatures on single crystal $SrTiO_3$ substrates by pulsed laser deposition and characterized for the microstructural and ferroelectric properties. The $SrTiO_3$ substartes etched by buffered oxide etch $(pH{\thickapprox}5.8)$ solution for 20s followed by the thermal annealing at $1000^{\circ}C$ for 1h showed the terrace ledges with a 0.4nm height. The $SrRuO_3$ bottom electrodes with a thickness of 52nm grown on $SrTiO_3$ single crystal also exhibit a terrace ledge similar to that of $SrTiO_3$. The PZT thin films were grown with an epitaxial relationship and showed typical P-E hysteresis loops shown at the epitaxial films. The 56nm thick-PZT films deposited at $650^{\circ}C$ exhibit a remanent polarization $(p_r)$ of $80{\mu}C/cm^2$ and a coercive field $(E_c)$ of 160kV/cm.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권6호
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• pp.410-415
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• 1999

$Ba_{1-x}Sr_xTiO_3$ thin films with various ratio of Sr (X = 0.4, 0.5, 0.6) were grown $Pt/TiN/SiO_2/Si$ subastrate by RF magnetron sputtering deposition. As, Ag, and Cu films were deposited on $Ba_{1-x}Sr_xTiO_3$ thin films as top electrodes by using a thermal evaporator. The electrical properties of $Ba_{1-x}Sr_xTiO_3$ thin films for various compositions were characterized and the physical properties at interface between $Ba_{1-x}Sr_xTiO_3$ thin films and top electrodes were evaluated in terms of the work function difference. At x =0.5, the degradation of capacitance is lower to the other compositions. As negative biasapplied, the specimen with Cu top electrode has board saturation region and low leakage current since work function of Cu is bigger than other electrodes.$ Ba_{0.5}Sr_{0.5}TiO_3$ thin films with Cu top electrode, the dielectric constant was measured to the value of 354 at 1 kHz and the leakage current was obtained to the value of $5.26\times10^{-6}A/cm2$ at the forward bias of 2 V.

• 센서학회지
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• 제18권6호
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• pp.456-461
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• 2009

Perovskite-structure $Sr(Ti_{1-x}Fe_x)O_3$ thick films, in which x is 0.4 or 0.6, were prepared by normal ceramic process on alumina substrate. Electrical resistance was measured as a function of thermal treatment condition including atmosphere, time, and temperature. The resistance of $Sr(Ti_{1-x}Fe_x)O_3$ films is lower than those of $SrTiO_3$ or $SrFeO_3$ films. The temperature coefficient of resistance over $550^{\circ}C$ was measured to be 0 for the $Sr(Ti_{1-x}Fe_x)O_3$ films after thermal treatment at $1100^{\circ}C$ in air. The sensing property of the films was also measured as a function of temperature and gas such as $O_2$, CO, $CO_2$, NO and $NO_2$. $Sr(Ti_{1-x}Fe_x)O_3$ films showed a good sensing property for $O_2$, but no sensing signal for CO, $CO_2$, NO and $NO_2$.