• Journal of the Korean Ceramic Society
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• v.40 no.4
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• pp.380-384
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• 2003

The effects of the mole concentrations of precursor solution on the microstructure and dielectric properties of sol-gel deposited $Ba_{0.85}$S $r_{0.15}$Ti $O_3$(BST) thin films have been investigated. The films were of single perovskite phase with strong (100) preferred orientation when grown on LaNi0$_3$ buffered Pt/Ti/ $SiO_2$Si substrates using a diluted precursor solution. Variation of the precursor solution concentration resulted in a different microstructure and, in turn, affected the tunability of the sol-gel deposited films. It was observed that leakage currents increased asymmetrically for the negative and positive bias voltage with decreasing thickness. Overall results suggest that those BST films have acceptable properties f3r applications as room-temperature tunable elements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.592-597
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• 2000

In this study (B $a_{0.5}$/S $r_{0.5}$)Ti $O_3$[BST(50/50)] ceramic thin films were prepared by the Sol-Gel method BST(50/50) stock solution was made and spin-coated on the Indium Tin Oxide(ITO)/glass substrate at 4000 rpm for 30 seconds. The coated films were dried at 35$0^{\circ}C$ for 10 minutes and annealed at 650~75$0^{\circ}C$ for 1 hour. The microstructural properties of the BST(50/50) thin film were studied by the XRD and AFM. The ferroelectric perovskite phase was formed at the annealing condition of 75$0^{\circ}C$ for 1 hour. Dielectric constant and loss of this thin were 370, 3.7% at room temperature respectively. The polarization switching voltage showed the good value of 3V. The leakage current density of the BST(50/50) thin film was 10$^{-7A}$c $m^2$with applied voltage of 1.5V. BST(50/50) thin film capacitors having good dielectric and electrical properties are expecting for the application to the dielectric material of DRAM.RAM.M.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.16-19
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• 2002

(Ba,Sr)TiO3(BST) thin film is an attractive material for the application in high-density dynamic random access memories (DRAMs) because of the high relative dielectric constant and small variation in dielectric properties with frequency. In this study, (Ba0.6,Sr0.4)TiO3 thin films on Pt/Ti/SiO2/Si substrates were deposited by a sol-gel method and the CF4/Ar inductively coupled plasma (ICP) etching behavior of BST thin films had been investigatedby varying the process parameters such as chamber pressure, ICP power, and substrate bias voltage. To analysis the composition of surface residue following etching BST films etched with different Ar/CF4 gas mixing ratio were investigated using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.33-36
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• 1999

In this paper, $Ba_{0.5}$Sr$_{0.5}$TiO$_3$ thin-films were prepared on Pt/Ti/Si0$_2$/Si substrates by RF magnetron sp-uttering method. We investigated electric and dielectric properties of BST thin-films with various ann-ealing temperature using in-sute RTA. Deposition conditions of BST films were set substrate temperat-ure, 30$0^{\circ}C$ and working gas ratio, Ar:O$_2$=90:10. After BST films deposited, we fabricated a capacitor of MIM structure with Al top electrode for measurement. Post-annealing using RTA performed at 40$0^{\circ}C$, $600^{\circ}C$, 80$0^{\circ}C$ for 60 sec, respectively. Also we exacted crystallization and composition of BST thin-films by XRD analysis. In measurement result, this capacitors showed a dielectric constant of about 200 at 1MHz and leakage current density of 5$\times$10$^{-8}$ A/$\textrm{cm}^2$ at 1.5V Microstructure of BST thin-films exhibited effective quality in low-temperature annealed 71ms than high-temperature annealed 71ms.s.s.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.2
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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) thin films were prepared on ITO-coated glass by sol-gel method. Perovskite phase formation temperature of BST thin films seemed to be higher than $600^{\circ}C$. Peaks of perovskite phase shift to high diffraction angles as the Sr/(Ba+Sr) ratio was increased, due to the smaller ionic size of $Sr^{2+}$ than $Ba^{2+}$ . As a heating temperature was increased, the grain became coarser. And as Sr/(Ba + Sr) ratio was increased, the grain became finer. Dielectric constants of the BST(50/50) thin film are higher and dielectric losses of that are lower than those of the others. Dielectric constant and dielectric loss of the BST(50/50) thin film were 652 and 0.042 at 1kHz, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.119-120
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• 1993

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.57-57
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.17-17
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.113-113
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• 1994

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.244-247
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• 2002

NdBaCuO thin films were prepared on $SrTiO_{3}$ substrates by RF magnetron sputtering. These as-grown films were classified into 3type. The resistivity of the deposited films are usually lower than of the YBCO film. The Tc (onset) and Tc (R=0) in the optimized thin films are as high as 90 and 80K, respectively. These as-grown films are highly uniform and semi-trans parent and have a room temperature resistivity of $0.3m{\Omega}cm$.