• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.115.1-115
• /
• 2003

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.185-188
• /
• 1999

Biepitaxial Y$_1Ba_2Cu_3O_{7-x}$ (YBCO) and La$_{0.2}Sr_{0.8}MnO_3$ (LSMO) thin films have been prepared on SrTiO$_3$ buffer layer and MgO seed layer grown on Al$_2O_3$(11${\bar{2}}$0)substrates by dc-sputtering with hollow cylindrical targets, respectively. We charaterized Josephson properties and significantly large magnetoresistance in YBCO and LSMO films with 45$^{\circ}$ grain boundary junction, respectively. The observed working voltage (I$_cR_n$) at 77 K in grain boundary junction was below 10${\mu}$V, which is typical I$_cR_n$ value of single biepitaxial Josephson junction. The field magnetoresistance ratio (MR) of LSMO grain boundary juncoon at 77K was enhanced to 13%, which it was significant MR value with high magnetic field sensitivity at a low field of 250 Oe. These results indicate that inserting the insulating layer instead of the grain boundary layer with metallic phase can be possible to apply a new SIS Josephson junction and a novel magnetic device using spin-polarized tunneling junction.

• Electrical & Electronic Materials
• /
• v.9 no.4
• /
• pp.336-343
• /
• 1996

We have studied the preparation and the properties of $Ba_{1-x}$Sr$_{x}$TiO$_{3}$(BST) thin films by using the sol-gel method. Through the comparison of the effects of various solvents and additives in making solutions, we establish the production method of the stable solution which generates the high quality of BST film. We also set up the heat-treatment conditions for depositing the BST thin film through the TGA and XRD analyses. Through the comparison of the surface conditions of BST films deposited on Pt/Ta/SiO$_{2}$/Si and Pt/Ti/SiO$_{2}$/Si substrates, we find that Ta is more efficient diffusion barrier of Si than Ti so that Ta layer prevents the formation of hillocks. We fabricate the planar type capacitor and measure the dielectric properties of the BST thin film deposited on the Pt/Ta/SiO$_{2}$/Si substrate. Dielectric constant and dielectric loss tangent at 1V, 10kHz, and leakage current density at 3V of the BST thin film are 339, 0.052 and 13.3.mu.A/cm$^{2}$, respectively.ely.

• Applied Chemistry for Engineering
• /
• v.8 no.4
• /
• pp.589-594
• /
• 1997

Superconducting $YBa_2Cu_3O_y$ thin films were prepared at the deposition temperature of $650^{\circ}C$ under oxygen partial pressure of 0.0126 Torr on Si(111) and SrTiO3(100) substrates by chemical vapor deposition technique using $\beta$-diketonates of Y, Ba and Cu as source materials. The thin film fabricated on $SrTiO_3(100)$ had a $T_{c,onset}$ of 91K and $T_{c.0}$ of 87K. The thin film prepared on Si(111) had a $T_{c,onset}$ of 91K but didn't have a $T_{c.0}$ at liquid nitrogen boiling point(77.3K). Dense and two-dimensionally well alligned microstructure was developed for the film deposited on $SrTiO_3(100)$ substrate whereas a relatively porous and randomly distributed microstructure was developed for the film prepared on Si(111) substrate.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1621-1623
• /
• 2004

The $Pb(Zr_{0.52}Ti_{0.48})O_3/(Ba_{0.6}Sr_{0.4})TiO_3$ [PZT(52/48)/BST(60/40)] heterolayered thin films were deposited on Pt/Ti/$SiO_2$/Si substrates by using the RF sputtering method with RF powers of 60,70,80,90[W]. All thin films showed the peaks of the tetragonal phase. Increasing the RF power, dielectric constant and loss of the PZT(52/48)/BST(60/40)] heterolayered thin films were decreased. The thickness ratio of PZT and BST thin films was 1/1. The relative dielectric constant and the dielectric loss of the PZT(52/48)/ BST(60/40) heterolayered thin films were 562 and 13%, respectively.

• Korean Journal of Materials Research
• /
• v.6 no.5
• /
• pp.449-456
• /
• 1996

BaO, SrCI2.6H2O 그리고 Ti(OPri)4를 출발 원료로 사용하여 균일한 BaxSr1-xTiO3(BST) 솔을 합성하였고, BST 박막을 회전 코팅 법으로 Si 및 Pt/Ti/SiO2/Si 기판위에 제조하였다. 적외선 및 NMR 스펙트럼 분석으로 킬레이션 조제로 사용한 acetylacetone(AcAc)이 엔올 형태로 Ti-알콕사이드와 결합하여 솔 안정화에 기여함을 확인하였다. Xedrogel에 대한 DT/TGA 및 적외선 스펙트럼 결과로부터 페로브스카이트 상생성이 $600^{\circ}C$ 이상에서 이루어짐을 관찰하였다. $700^{\circ}C$에서 열처리한 박마은 -300(10 KHz)의 상대유전율을 나타내었고, 결정립의 저항 및 입계의 병렬 RC 성분으로 등가회로를 구성할 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.28-28
• /
• 2007

Ferroelectric $(Ba_{0.5}Sr_{0.5})TiO_3$ (BST) thin films of thickness 500nm were deposited on $LaAlO_3$, (LAO) substrates by at $800^{\circ}C$. BST films were characterized for structure using X-ray diffraction (XRD). The surface morphology and thickness of BST the films were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). We measured the dielectric properties at microwave frequencies (1~3 GHz) using a symmetrical stripline resonator with shorted ends and terahertz frequencies (0.2~2.5 THz) using a time-domain terahertz spectroscopy. The real and imaginary parts of the complex dielectric constant of the BST thin films on LAO substrates were in agreement with those previously reported.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.776-779
• /
• 2004

The dielectric and electrical characteristics of Ce doped (Ba0.6Sr0.4)TiO3 (BST) thin films were investigated as a function of Ce content. Both atomic force microscopy (AFM) and x-ray diffraction (XRD) analysis showed that increasing the Ce doping ratio causes the decrease in grain size while the surface remains smooth and crack-free. The dielectric properties of the Ce doped BST films were found to be strongly dependent on the Ce contents. The dielectric constant and dielectric loss of the BST films decreased with increasing Ce content. However, it was also found that, compared with undoped films, the increase of Cecontent improves the leakage-current characteristics. The improvement of the electrical properties of Ce-doped BST films may be related to the decrease in the concentration of oxygen vacancies. The figure of merit (FOM) reached the maximum value of 48.9 at the 1 mol % of Cedoping. The dielectric constant, loss factor, and tunability of the 1 mol% Ce doped Ba0.6Sr0.4TiO3 thin films were 320, 0.011, and 46.3%, respectively.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.30.1-30.1
• /
• 2011

Multiferroic thin films with composition $0.9BiFeO_3-0.1Ba(Cu_{1/3}Nb_{2/3})O_3$ were epitaxially grown by pulsed laser deposition on $SrRuO_3(001)/SrTiO_3$ (000) substrate $0.9BiFeO_3-0.1Ba(Cu_{1/3}Nb_{2/3})O_3$, which is assumed to be morphotropic phase boundary (MPB), that showed superior dielectric, ferroelectric and magnetic properties in our study on polycrystalline films. The structures of epitaxially grown films were characterized by means of XRD. From P-E measurements, samples exhibited typical ferroelectric hysteresis loops and large remnant polarization, whose value is much larger than those of pure BFO film. The enhancement of dielectric, ferroelectric, magnetic properties was attributed to the structural distortion induced by the BCN addition and the high physical stress effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.266-267
• /
• 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.