• 한국초전도ㆍ저온공학회논문지
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• 제6권3호
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• pp.16-20
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• 2004

YB $a_2$C $u_3$$O_{7-x}$ (YBCO) films were deposited on (100) SrTi $O_3$ single crystal substrates by a metal organic chemical vapor deposition (MOCVD) system of hot-wall type using single liquid source. Under the condition of the mole ratio of Y(tmhd)$_3$:Ba(tmhd)$_2$:Cu(tmhd)$_2$= 1:2.1:2.9. the deposition pressure of 10 Torr. the MO source line speed of 15 cm/min. the Ar/ $O_2$ flow rate of 800/800 sccm. YBCO films were prepared at the deposition temperatures of 780∼89$0^{\circ}C$. In case of the YBCO films with 2.2 ${\mu}{\textrm}{m}$ thickness deposited for 6 minutes at 86$0^{\circ}C$. XRD pattern showed complete c-axis growth and SEM morphology showed dense and crack-free surface. The atomic ratios of Ba/Y and Cu/Ba in the film were 1.92 and 1.56. respectively. The deposition rate of the film was as high as 0.37 ${\mu}{\textrm}{m}$/min. The critical temperature ( $T_{c.zero}$) of the film was 87K. The critical current of the film was 104 A/cm-width. and the critical current density was 0.47 MA/$\textrm{cm}^2$. For the thinner film of 1.3 ${\mu}{\textrm}{m}$ thickness. the critical current density of 0.62 MA/$\textrm{cm}^2$ was obtained.d.

• 센서학회지
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• 제9권1호
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• pp.83-89
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• 2000

TFELD의 절연층으로 사용하기 위해 ITO 유리위에 BST박막을 rf 마그네트론 스퍼터링법으로 증착시켰다. $O_2/(Ar+O_2)$의 혼합비는 10%, 기판온도는 상온에서 $500^{\circ}C$까지 변화를 주었고, 분위기압은 5 mTorr에서 30 mTorr까지 변화시켰다. 다양한 증착조건에서 성장된 BST박막의 전기적, 광학적, 구조적 및 화학량론적인 특성을 조사하였다. BST박막성장의 최적조건은 기판온도 $400^{\circ}C$, 분위기압 30 mTorr에서 구할 수 있었다. 주파수 1 kHz에서 비유전율은 254였고, 누설전류밀도는 5 MV/cm의 전계에서 $3.3{\times}10^{-7}\;A/cm^2$이하로 나타났으며, 가시광영역에서 광투과율은 82%였다.

• 마이크로전자및패키징학회지
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• 제3권1호
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• pp.33-40
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• 1996

MOD법에 의해 BST박막을 제조하고 전기적 특성을 측정함으로써 마이크로 회로에 적용가능성을 타진하였다. MOD 공정의 선구물질로서 barium neodecanoate, strontium 2-ethylhexanoate 및 titanium dimethoxy 야-2-ethylheanoate를 합성하였다, 합성된 선구물 질들을 Ba0.5Sr0.5TiO3가 되도록 화학양론적으로 혼합하여 공통용매인 p-xylene에 녹인다음 기판위에 spin coating 방법으로 박막을 형성하여 건조하고 소성하였다. 사용된 기판은 ITO/glass, Pt/SiO2/Si, Pt/Ti/SiO2/Si 및 Pt foil을 사용하였다. 소성 속도를 빨리했을 경우 소성속도를 느리게 했을때에 비하여 훨씬 균일하고 치밀한 박막을 얻을수 있었다, 여러 가 지 제조조건의 변화에 따른 유전상수 I-V 특성 및 C-V 측성 등의 전기적 특성을 측정하고 고찰하였다.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.36.2-36
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• 2003

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
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• pp.116.2-116
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• 2002

• 한국재료학회지
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• 제17권7호
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• pp.386-389
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• 2007

The dielectric properties of $(Ba_{0.5}Sr_{0.5})TiO_3$ ferroelectric thin films have been investigated according to the substrates in order to optimize the their properties. MgO, r-plane sapphire, and poly-crystalline sapphire (Alumina) substrates have been used to deposite $(Ba_{0.5}Sr_{0.5})TiO_3$ ferroelectric thin films by RF magnetron sputtering. The BST thin films deposited on the single crystal (100)MgO substrates have high tunability and low dielectric loss. These results are caused by a low misfit between the lattice parameters of the BST films and the substrate. The BST films deposited on r-plane sapphire have relatively high misfit, and the tunability of 17% and dielectric loss of 0.0007. To improve the dielectric properties of the BST films, the post-annealing methods has been introduced. The BST films deposited on (100)MgO, (1102)r-plane sapphire, and poly-crystalline sapphire substrates have best properties in post-annealing conditions of $1050^{\circ}C$, $1100^{\circ}C$, and $1150^{\circ}C$, respectively. The different optimal post-annealing conditions have been found according to the different misfits between the films and substrates, and thermal expansion coefficients. Moreover, the films deposited on alumina substrate which is relatively cheap have a good tunability properties of 23% by the post-annealing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.266-267
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• 2007

$Ba_{0.5}Sr_{0.5}TiO_3$(BST) films with different deposition temperatures were deposited on $Al_2O_3$ substrate by Nd:YAG Pulsed Laser Deposition(PLD). The deposition conditions to achieve high crystal structures and dielectric properties were optimized for both techniques. The structural characterization on the BST thin films was performed by X-Ray Diffraction(XRD) and Atomic Force Microscopy (AFM). Effects of post-deposition annealing of BST films were investigated. The best dielectric properties were obtained on $800^{\circ}C$ deposited BST film with post-deposition annealing at $1100^{\circ}C$ in flowing $O_2$ atmosphere for 2hours.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.263-266
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• 2001

In this paper, we investigated dielectric properies for BST thin films that was deposited on MgO/Si substrates using RF magnetron sputtering. In here, MgO film was used to perform that a diffusion b arrier between the BST film and Si substrate and a buffer layer to assist the BST film growth. A d eposition condition for MgO films was RF Power of 50W, substrate temperature of room temperature and the working gas ratio of Ar:O$_2$ were varied from 90:10 to 60:47. Finally we manufactured the cap acitor of Al/BST/MgO/Si/Al structure to know electrical properties of this capacitor through I-V, C-V measurement. In the results, C-V aha racteristic curves was shown a ferroelectric property so we measured P-E. A remanent poliazation and coerceive electric field was present 2$\mu$C/cm$^2$ and -27kV/cm respectively at Ar:O$_2$=90:10. And a va clue of dielectric constant was 86 at Ar:02=90:10.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.13-17
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• 2005

The Pb(Zr/sub 0.52/Ti/sub 0.48/)O₃/(Ba/sub 0.6/Sr/sub 0.4/)TiO₃[PZT/BST] heterolayered thin films were deposited on Pt/Ti/SiO₂/Si substrates by using the RF sputtering method with different RF power. The PZT/BST heterolayered thin films had the tetragonal structure of the PZT phase and BST phase. Increasing the RF power. the intensity of the PZT (100), (110) peaks and BST (111) peaks were decreased and the intensity of the BST (100), (110) peaks were increased. The thickness ratio of the top layered BST thin film and the bottom layered PZT thin film was 2 to1. The atomic concentration of the Ba, Sr, Pb. Zr, Ti atoms were constant in the PZT thin films and BST thin films, respectively. The Pt atom was diffused to the PZT region in the PZT/BST heterolayered thin films deposited at condition of 60[W] RF power. Increasing the frequency, dielectric constant and loss of the PZT/BST heterolayered thin films were decreased. The dielectric constant and loss of the PZT/BST heterolayered thin films deposited with RF power of 90[W] were 406 and 3%, respectively.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.504-510
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• 2002

Recently, thin film capacitors of high dielectric constant and low leakage current are applied to integrated devices. In this study, (Ba, Sr)$TiO_3$ (BST) thin films for low cost were prepared by Sol-Gel method. BST solution was spin-coated on Pt/$SiO_2$/Si substrate at 4,000 rpm for 10 seconds. Coating process was repeated 3 times and then sintered at $700^{\circ}C$ for 30 minutes. Structural and electrical characteristics of each specimen were analyzed by TG-DTA, SEM, fractal phenomenon, voltage-current and dielectric factor. Thickness of BST ceramics thin films are about 2,600~2,800 ${\AA}$ at depositing 3 times. Dielectric constant of thin films was decreased in 1 kHz~1 MHz. Dielectric constant and loss to frequency were 250 and 0.02 in $(Ba_{0.7}Sr_{0.3})TiO_3$ (BST3). Leakage current of BST3 was $10^{-9}\sim10^{-11}$/ A under 3 V.