• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.205-206
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• 2006

(BaSr)$TiO_3$ thick films were prepared by tape casting method, using $BaTiO_3$ and $SrTiO_3$ powder slurry in order to investigate dielectric properties. With MgO additives, the sintering density was 5.8 $g/cm^3$ and the BST sample exhibited the maximum dielectric constant, tunability at temperatures near phase transition point. Dielectric loss be on the decrease because the interface is not a pore. BST sample be applicable on tunable device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.243-246
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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 structural, dielectric and electrical properties of BST thin films were investigated with Ar/O$_2$ ratio. Dielectric constant and dielectric loss of the BST thin film were about 1020 and 2.0[%], respectively. (at RF power 80W, post annealing temperature $650^{\circ}C$, deposition pressure of 5mTorr and Ar/O$_2$=80/20). For the BST(Ar/O$_2$=80/20) thin film with Polarization switching cycles of 10$^{10}$ , remanent polarization and coercive field were 0.084[$\mu$C/cm$^2$], 1.954[kV/cm], respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.309-313
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• 1997

(Ba$_{x}$Sr$_{l-x}$)TiO$_3$(BST) thin fi1ms with various Ba/Sr ratios were deposited on Pt(80nm)/SiO$_2$(100nm)/Si by RF magnetron sputtering. BST thin films which have x=0.6, 0.5, 0.4 were studied dielectric properties with temperature variation. The frequency was used from 100Hz to 1MHz for measuring dielectric constant. The measurement conditions of dielectric constant with Temperature Variation were 1KHz and 2$0^{\circ}C$. As a result, the dielectric constant of BST thin film was about 425 and loss factor was 0.013. Also, with increasing Temperature, the dielectric constants of BST thin films were gradually decreased.sed.

• 한국결정성장학회지
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• 제11권2호
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• pp.60-66
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• 2001

($Ba_x$$Sr_{1-x}$)$TiO_3$ (x=0.9, 0.7, 0.5)박막을 졸-겔법으로 ITO-coated glass기판 위에 제조하였다. BST의 perov-skite상 생성온도는 $600^{\circ}C$ 이상이며 Sr함량이 증가할수록, $Ba^{2+}$ 이온보다 작은 $Sr^{2+}$ 이온에 의해 perovskite상들의 피크가 높은 회절 각도로 이동하였다. 그리고 온도가 증가할수록 결정립은 조대화 되었고, Sr 함량이 증가할수록 결정립은 미세화 되었다. BST(50/50)의 유전상수 값은 다른 두 조성보다 큰 값을 나타내고 유전손실 값은 더 낮았다. 1 kHz때의 BST(50/50)박막의 유전상수 및 유전손실 값은 각각 652와 0.042였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1879-1881
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• 1999

(Ba,Sr)$TiO_3$[BST] thin films were fabricated on Pt/Ti/$SiO_2$/Si substrate by RF sputtering. We investigated the effects of substrate temperature on the structural and dielectric properties of BST thin films. Increasing the substrate temperature, barium multi titanate phases were decreased, and BST (100), (200) peaks were increased. The relative dielectric constant and dielectric loss of the BST thin films at the substrate temperature of $500^{\circ}C$ were 300 and 0.018, respectively at l[kHz]. In all films, the dielectric constants decreased. Dielectric losses increased as increasing the frequency. The switching voltage was 5V of the BST thin films at the substrate temperature of $500^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.18-21
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• 2004

An alkoxide-based sol-gel method was used to fabricate $Ba_{0.6}Sr_{0.4}TiO_3$ thin films doped by Bi from 5 to 20 mol% on a $Pt/Ti/SiO_2/Si$ substrate. The structural and dielectric properties of BST thin films were investigated as a function of Bi dopant concentration. The dielectric properties of the Bi doped BST films were strongly dependent on the Bi contents. The dielectric constant and dielectric loss of the films decreased with increasing Bi content. However, the leakage current density of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin film showed the lowest value of $5.13{\times}10^{-7}\;A/cm^2$ at 5 V. The figure of merit (FOM) reached a maximum value of 32.42 at a 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films. The dielectric constant, loss factor, and tunability of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films were 333, 0.0095, and 31.1%, respectively.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.141-144
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• 2011

We report the synthesis of $SrTiO_3$, $BaTiO_3$ and $Ba_xSr_{1-x}TiO_3$ (BST) nanoparticles (NPs) in various compositions (x = 0.25, 0.5 and 0.75) by an inorganic sol-gel method under a basic condition. Highly crystalline nanoparticles were formed at the reaction temperature of 25 - $100^{\circ}C$ from a stabilized titanium alkoxide in tetramethylammonium hydroxide (TMAH) and barium or strontium acetate in aqueous solution. Morphology and particle structure of the synthesized BST NPs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The BST nanoparticles in various compositions were monodispersed without mutual aggregation, and their average sizes were in the range of 70 - 80 nm. Furthermore, they showed highly crystallized perovskite phase over the whole composition range from $SrTiO_3$ to $BaTiO_3$. We also proposed a mechanism for the low-temperature formation of BST NPs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.51-54
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• 2000

In this paper, $Ba_{0.5}$Sr$_{0.5}$TiO$_3$ thin films were prepared on Pt/Ti/SiO$_2$/Si substrate by RF magnetron sputtering method. We investigated effect of deposition conditions (especially RF input power) on structural properties of BST thin films. Deposit conditions of BST films were set working gas ratio, Ar:O$_2$= 70 : 30, working pressure 10mTorr, and RF input power 25W, 50W, 75W and 100W. Post-annealing using rapid thermal annealing(RTA) performed at 45$0^{\circ}C$, 55$0^{\circ}C$, $650^{\circ}C$, and 75$0^{\circ}C$ in oxigen ambient for 60 sec, respectively. The structural properties of BST films on Pt/Ti/SiO$_2$/Si substrate analysed by X-ray diffraction(XRD).).).

• 전자공학회논문지D
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• 제36D권4호
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• pp.56-62
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• 1999

본 연구에서, (Ba,Sr)TiO\sub 3\ 박막이 rf 전력, dc 바이어스 전압 및 반응로 압력과 같은 식각 공정 변수를 변화하여 ICP에서 Cl\sub 2\Ar 가스 혼합비에 따라 식각되었다. 0.2의 Cl\sub 2\/(Cl\sub 2\+Ar) 가스 혼합비, 600 W의 rf 전력,250 V의 dc 바이어스 전압 및 5 mTorr의 반응로 압력의 공정 조건하에서 식각율은 56nm/min이었다. 이때 Pt, SiO\sub 2\ 막에 대한 BST 박막의 식각 선택비는 각각 0.52, 0.43이었다. 식각된 BST 박막의 표면반응은 XPS로 분석하였다. Ba는 BaCl\sub 2\ 와 같은 화학적인 반응과 물리적인 스퍼터링에 의해 제거되었다. Sr의 제거는 Sr과 Cl의 화확적인 반응보다 Ar 이온 충격이 더 효과적이었다. Ti는 TiCl\sub 4\ 와 같은 화학반응에 의해 용이하게 제거되었다. XPS 분석 결과를 비교하기 위하여 SIMS의 분석을 수행하여 비교한 결과 동일한 결론을 도출하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권12호
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• pp.555-559
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• 2006

Using the $Ba_{0.5}Sr_{0.5}TiO_3$(BST) powders prepared by the Sol-Gel method, the BST thick films were fabricated on the $Al_2O_3 $substrates coated with Pt by the screen printing method. Compared with pure BST thick films, the structural and dielectric properties of the BST thick films doped with $1{\sim}10$ wt % MgO were investigated. It was observed that the Mg substitution into BST causes a shift in the cubic-tetragonal BST phase transition peak to a lower temperature. The microstructure of the BST substituted with Mg was homogeneous and dense. Mg substitution into BST had a significant effect on the grain size reduction. Dielectric constant was decreased with increasing the MgO content and temperature. In the case of BST thick films doped with 1 wt% MgO, the relative permittivity and dielectric loss were 1581 and 1.4 % at 1 MHz.