• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.148-151
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• 1995

Excimer laser has been used to fabricate superconducting YBa$_2$Cu$_3$O$\sub$7-x/(YBCO) thin films on various substrates. An XeCl excimer laser with an wavelength of 308 nm was used to deposit both buffer layer and superconducting thin film on sapphire substrate. The characterizations of the interface between thin film and substrate were performed. The interfacial properties of thin films on buffered sapphire and on bare sapphire were compared. With a 20 nm PrBa$_2$Cu$_3$O$\sub$7-x/(PBCO) buffer layer, no diffusion layer was observed between film and substrate while the diffusion layer with about 30 nm thickness was observed between film and sapphire without buffer layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.743-745
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• 2002

Pyroelectric and dielectric properties of modified PZT thin film and bulk ceramics were studied. In case of bulk specimens were prepared by conventional ceramic process and thin films with same composition and (111) preferred orientation were prepared by the sol-gel process. Their crystal structure, pyroelectric and dielectric properties were investigated after poling at $150^{\circ}C$ for 30 min for bulk ceramics and no poling treatment, respectively. Dielectric constants and losses of bulk and thin film were 600, 875 and 0.028, 0.025, respectively. Pyroelectric coefficients obtained were $50nC/cm^2K$ and $30nC/cm^2K$, respectively.

• Progress in Superconductivity
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• v.6 no.1
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• pp.32-36
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• 2004

To investigate the influence of strip width and inter-strip separation on the ac loss, arrays of parallel strips with different widths and separations were prepared. Studies on the hysteresis-loss characteristics of multifilamentary YBCO films were performed. The local magnetic field due to magnetization currents is measured by a scanning Hall probe microscope. Based on these results a conceptual design for a low loss YBCO coated conductor is suggested.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1123-1132
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• 1994

Bi-Sr-Ca-Cu-O superconductor thin films were prepared on MgO and LaAlO3 substrates by MOCVD technique. The films deposited on MgO and LaAlO3 substrates became superconducting at 64 K and 70 K respectively. The measured critical current density of thin film deposited on LaAlO3 substrate was around 104 A/$\textrm{cm}^2$. After annealing at $700^{\circ}C$ for 3 hours, the critical transition temperature(Tc) of films deposited on LaAlO3 was changed from 70 K to 74 K.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.715-722
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• 1994

Off-axis supttering using shielder was used to efficiently prevent negative oxygen ions from resputtering deposited films. In this method, the substrate was located vertically to the target and shielded by the semicircled steel plate. By using this method, the resputtering could be reduced, and 2223 high-Tc phase could be formed at the lower substrate temperature and in the broader temperature region. As increasing the substrate temperature, 2212, 2223, 2212 superconducting phases were formed by turns. 2223 phase was formed above 2$\times$10-2 torr, and 2212 phase was formed above 4$\times$10-2 torr.

• Journal of the Korean Ceramic Society
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• v.33 no.3
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• pp.313-320
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• 1996

We have fabricated an in-plane aligned a-axis oriented YBa2Cu3O7-x (a-YBCO) thin film on a LaSrGaO4(100) substrate with a PrBa2Cu3O7-x(PBCO) template layer by two step plused laser deposition using 308 nm XeCl excimer laser. A YBCO layer and PBCO layer grown at low temperatures were used as template layers. We have investigated the effect of the deposition temperature of template layers on the superconducting and struc-tural properties of in-plane aligned a-YBCO thin films. An optimal deposition temperature of the PBCO template layers was 630. In-plane aligned a-YBCO thin films showed an anisotropy ratio in resistivity of 11.5 and a zero resistance temperature of 88 K.

• Progress in Superconductivity
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• v.6 no.2
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• pp.99-103
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• 2005

For ac applications a detailed understanding of the ac power losses associated with different conductor configurations is of crucial importance. YBCO thin films were divided into parallel filaments with widths of 1, 2, and 4 mm to reduce hysteresis losses. The measured hysteresis losses show a linear relationship between the strip width and hysteresis loss as anticipated. The influence of different inter-filament separations on the hysteresis loss is investigated.

• Progress in Superconductivity
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• v.12 no.1
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• pp.32-35
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• 2010

Potassium doped $BaFe_2As_2$ superconducting thin films by using an ex situ pulsed laser deposition technique were fabricated in various conditions to find out an optimal growth condition. Controlled conditions were annealing temperature, annealing time, and mass of potassium. The $Ba_{1-x}K_xFe_2As_2$ thin films which has most good quality is fabricated at a condition of annealing temperature at $700^{\circ}C$, annealing time of 60 minutes, and 0.6 g of potassium lumps. In this condition we were able to fabricate good quality films with high transition temperature of ~ 39 K.

• Progress in Superconductivity
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• v.9 no.2
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• pp.188-192
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• 2008

We investigated the size effect on quench development in $Au/YBa_2Cu_3O_7$ (YBCO) thin film meander lines on sapphire substrates. The meander lines were fabricated by patterning YBCO films coated with gold layers. The lines were subjected to simulated AC fault current, and immersed in liquid nitrogen during the experiment. After the initial rapid rise, the resistance increased moderately and then slowly. In 4 inch-diameter meander lines, the period during which the resistance increased moderately was considerably longer than in 2 inch-diameter line. Moderate increase of resistance was originated from quench propagation. The film temperature was about 180 K at the point when the propagation was completed. The rate of resistance increase after the quench completion was not affected by the film size.

• 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 $0.3m{\Omega}cm$.