• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.441-447
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• 1995

Ba0.65Sr0.35TiO3 (BST) thin films were deposited on Pt/SiO2/Si(100) substrate by rf magnetron sputtering. The substrate temperature changed from 35$0^{\circ}C$ to 55$0^{\circ}C$ and crystalline BST thin films were deposited above 45$0^{\circ}C$. Most of the films had (111) preferred orientation regardless of deposition temperature, but the films changed to (100) preferred orientation as gas pressure increased. The dielectric constant increased with increasing substrate temperature and film thickness, and ranged from 100 to 600 at room temperature. The leakage current increased as substrate temperature increased or as film thickness decreased.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.349-356
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• 1988

The PTCR characteristics of (Ba0.8Pb0.2)TiO3 ceramics prepared by the molten salt sysnthesis (MSS) method have been investigated as a function of the amount of Nb2O5 dopant and KCl flux. When the weight ratio of KCl to raw material is 0.8, the resistivity at room temperature decreases with increasing amount of Nb dopant up to 0.6 atom%. It can be explained by compensation for electrons due to Nb+5 ion and holes due to K+ ion. The resistivity of (Ba0.8Pb0.2)(Ti0.994Nb0.006)O3 ceramics at room temperature decreases with increasing the ratio of KCl to raw material up to 0.6, and then increases. These results can be explained by the effect of K+ ion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.289-292
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• 1997

BaTiO$_3$thin film capacitor were prepared on Pt(100)/SiO$_2$/Si(100)wafer by RF sputtering technique. Dielectric and electrical characteristics of the thin film capacitor are investigated. The Dielectric constant and loss were about 683 and 5[%], respectively. We found that the leakage current of thin film capacitor is depend on RF power during deposition. Because of increase of activation energy, leakage current inclosed at high RF power and sheet resistivity of the films was decreased. Swithching voltage of thin film capacitor was 4.4[V]

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.3
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• pp.75-75
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• 2001

Si₃N₄/SiO₂/Si₃N₄ 멤브레인에 의해 실리콘 기판으로부터 열차단된 비냉각 초전형 박막 (Ba,Sr)TiO₃ 적외선 검지기를 제작하고, 적외선 검지기의 특성을 논의하였다. 25℃의 공기중에서 쵸핑주파수가 1 ㎐일 때 적외선 검지기는 약 168.8 V/W의 비교적 높은 전압 감응도를 나타내었으나, 매우 작은 신호대잡음비 때문에 약 2.6×10⁴㎝·㎐/sup 1/2//W의 낮은 비검지도를 나타내었다. 또한 출력파형의 쵸핑주파수 및 온도 의존성에 대한 정성적인 해석으로부터 적외선 검지기의 열잡음전압 및 열시정수가 모두 상당히 크다는 것을 알 수 있었다.

• Journal of the Korean Ceramic Society
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• v.23 no.6
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• pp.66-70
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• 1986

The calcining temperature ranging from 900$^{\circ}C$ to 1300$^{\circ}C$ affected on the planar coupling factor and resonance characteristics of BaTiO3 ceramics doped with 0.2 wt% MnO2 have been investigated. Dielectric constant planar coupling factor and anti-resonance frequency of the sample increased with the calcining temperature up to 1,200$^{\circ}C$ and decreased above that temperature but the resonance frequency decreased slightly with the increasing calcining temperature. The planar coupling factor and anti-resonance frequency increased with the sintered density and dielectric constant while the resonance frequency was almost constant. The resonance and anti-resonance frequency increased with the sample temperature.

• Journal of the Microelectronics and Packaging Society
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• v.4 no.2
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• pp.47-54
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• 1997

Pt/SiO2/Si을 기판으로 사용하고 RF 마그네트론 스퍼터링에 의한 (Ba, Sr)TiO3 (BST) 씨앗층을 약 10nm 정도의 두께로 입힌 다음 그 상부에 화학 기상증착법으로 BST를 증착하여 BST seed layer가 CVD BST 박막의 특성에 미치는 영향을 조사하였다. 또한 급 속열처리가 BST 박막과 커패시터의 특성에 미치는 영향도 조사하였다. Seed layer와 급속 열처리에 의해 박막의 결정성이 향상되었으며 이로인해 유전상수가 증가되었고 주파수에 대 한 유전특성도 개선되었다. Seed layer를 도입함으로써 BST 박막과 Pt 하부전극 사이의 계 면에 존재하고 있는 산소부족\ulcorner이 사라짐을 확인할수 있었으며 이로 인해 Pt/BST/Pt 커\ulcorner 시터의 누설전류가 감소하였다. 또한 급속 열처리에 의해 BST/Pt 계면에서 트랩된 전자의 농도가 감소함으로써 누설전류 특성이 개선됨을 알수 있었다. Seed layer 위에 증착된 CVD BST 박막의 유전상수는 증착온도가 증가함에 따라 증가하였으나 누설전류도 같이 증가하 였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.379-382
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• 1998

(Ba, Sr)TiO$_3$[BST] thin films were fabricated on Pt/SiO$_2$/Si substrate by RF sputtering technique. The Mic개structure, dielectric and electrical properties of BST thin films were investigated with sputtering pressure. Dielectric constant and dielectric loss of the deposited thin film at sputtering pressure of 5 mTorr were about 91 and 1.9(%), respectively. Increasing sputtering pressure, leakage current was increased. It was found that leakage current of BST thin films was depended on the sputtering pressure.

• The Korean Journal of Ceramics
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• v.4 no.2
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• pp.68-71
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• 1998

The effect of Mn and Nb additions on the electrical properties of BaTiO$_3$ has been studied by means of equilibrium electrical conductivity as a function of temperature, oxygen partial pressure(Po$_2$) and composition. If the manganese ion is added to the normal Ti site, i.e. BaTi$_{1-x}Mn_xO_{\delta-6}$, the equilibrium conductivity shows strong evidence of acceptor-doped behavior. The conductivity minimum, corresponding to the transition from oxygen excess, p-type behavior to oxygen deficient, n-type behavior with decreasing Po$_2$, is displaced to lower Po$_2$ and is broadened and flattened. The partial replacement of Mn ion with Nb decreases the acceptor-doped effect and the total replacement exhibits a typical donor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped samples, for the p-type region, the electrical conductivity follows the 1/6th power dependence of oxygen partial pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.132-135
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• 1999

Recently, the ceramics of high permittivity are applied to DRAM and FRAM. In this study, (B $a_{x}$ S $r_{l-x}$)Ti $O_3$(BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/ $SiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$] for 30 minutes. Each specimen was analyzed structure and electrical characteristics. Thickness of BST ceramics thin films are about 2000($\AA$). Dielectric constant and loss of thin films was little decreased at 1[KHz] ~1[KHz]. Dielectric constant and loss to frequency were 250 and 0.02 in $Ba_{0.7}$S $r_{0.3}$Ti $O_3$. The properly of leakage current as the realation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.628-633
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• 2011

Studies on lead-free piezoelectrics have been attractive as means of meeting environmental requirements. We synthesized lead-free piezoelectric $(Bi_{1/2}Na_{1/2})TiO_3-Ba(Cu_{1/3}Nb_{2/3})O_3$ (BNT-BCN) ceramics, and their dielectric, piezoelectric, and strain behavior were characterized. As BCN with a tetragonal phase was incorporated into the rhombohedral BNT lattice, the lattice constant increased. A small amount of BCN increased the density and dielectric constant forming the complete solid solution with BNT. However, BCN above 10 mol% was precipitated into a separate phase, and which was detected with XRD. In addition, EDX measurement revealed that Cu in BCN was not distributed homogeneously but was accumulated in a certain area. A lower density with a large amount of BCN was attributed to the nonsinterable property of BCN with large tetragonaliy. The dielectric constant vs the temperature change and the strain vs the electric field indicated that the ferroelectric property of BNT was diminished and paraelectric behavior was enhanced with the BCN addition. BNT-7.5BCN showed a 0.11% unimorph strain with a 9.0 kV/mm electric field with little hysteresis.