• Progress in Superconductivity
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• v.13 no.2
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• pp.122-126
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• 2011

Superconducting $MgB_2$ thin films were fabricated by using a novel aerosol deposition technique wherein the pre-reacted powder is directly transformed into respective thin film. The formed thin films were characterized by X-ray diffraction technique and FE-SEM to understand its structure and morphology and the superconducting behavior has been characterized with the four probe resistivity measurement. The as-deposited thin films were formed into the frustrated amorphous structure, which were relaxed on the further heat treatment at $900^{\circ}C$ for 3 hrs. The relaxed amorphous $MgB_2$ thin films showed a comparatively high superconducting onset at about 38 K.

• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.20-25
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• 2018

Niobium nitride (NbN) superconducting thin films with the thickness of 100 and 400 nm have been deposited on the surfaces of silicon oxide/silicon substrates using a sputtering method. Their superconducting properties have been evaluated in terms of the transition temperature, critical magnetic field, and critical current density. In addition, the NbN films were patterned in a line with a width of $10{\mu}m$ by a reactive ion etching (RIE) process for their characterization. This study proves the applicability of the standard complementary metal-oxide-semiconductor (CMOS) process in the fabrication of superconducting thin films without considerable degradation of superconducting properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.81-83
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• 1992

The superconducting thin films deposited on $SiO_x$ substrate by R.F magnetron sputter using $YBa_2Cu_3O_x$ single target have been made and annealed at $940^{\circ}C$ for 30 min. The thickness of films were 1000-2000${\AA}$ with a rate of 20-25${\AA}/min$ and superconducting properties of thin films depended on the compositions of pre-annealed the thin films. It has been analyzed by SEM photo-analysis and X-ray diffraction patterns of these samples obtained under the various conditions of this sputtering methods. and recognized the supperconducting thin films by electric properties.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.329-331
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• 1995

Laser ablation was used to fabricate superconducting $YBa_2Cu_3O_{7-x}$ (YBCO) thin films on metallic substrates with an YSZ buffer layer. An ArF excimer laser with an wavelength of 193 nm was used to deposit both YSZ buffer layer and superconducting thin film. The characterizations of thin films were performed and compared. With a 200 nm YSZ buffer layer, c-axis orientation and $T_c$=85 K were obtained for a 200 nm-thick YBCO film.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.430-436
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• 1996

We have grown superconducting thin films on various substrates using a pulsed laser deposition (PLD) method. $YBa_2Cu_3O_7-\delta$ (YBCO) superconducting thin films with the superconducting transition temperature ($T_{c. offset}$) of 87K were grown on Si substrates using yittria-stabilized zirconia (YSZ) and $CeO_2$ double buffer layers. We have developed a large area pulsed laser deposition system. The system was designed to deposit up to 6 different materials on a large area substrate up to 7.5cm in diameter without breaking a vacuum. The preliminary runs of the deposition of YBCO superconducting thin films on $SrTiO_3$ substrate using this system showed a very uniform thickness profile over the entire substrate holder area. $T_{c}$ of the deposited YBCO thin film, however, was scattered depending on the position and the highest value was 85K.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.5-8
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• 2013

We have studied Hall effect for potassium (K)-doped $BaFe_2As_2$ superconducting thin films by analyzing the relation between the longitudinal resistivity (${\rho}_{xx}$) and the Hall resistivity (${\rho}_{xy}$). The thin films used in this study were fabricated on $Al_2O_3$ (000l) substrates by using an ex-situ pulsed laser deposition (PLD) technique under a high-vacuum condition of ~$10^{-6}$ Torr. The samples showed the high superconducting transition temperatures ($T_c$) of ~ 40 K. The ${\rho}_{xx}$ and the ${\rho}_{xy}$ for K-doped $BaFe_2As_2$ thin films were measured by using a physical property measurement system (PPMS) with a temperature sweep (T-sweep) mode at an applied current density of $100A/cm^2$ and at magnetic fields from 0 up to 9 T. We report the T-sweep results of the ${\rho}_{xx}$and the ${\rho}_{xy}$ to investigate Hall scaling behavior on the basis of the relation of ${\rho}_{xy}={A{\rho}_{xx}}^{\beta}$. The ${\beta}$ values are $3.0{\pm}0.2$ in the c-axis-oriented K-doped $BaFe_2As_2$ thin films, whereas the thin films with various oriented-directions like a polycrystal showed slightly lower ${\beta}$ than that of c-axis-oriented thin films. Interestingly, the ${\beta}$ value is decreased with increasing magnetic fields.

• Korean Journal of Materials Research
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• v.1 no.1
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• pp.54-61
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• 1991

YBCO films deposited on MgO(100) and Si(100) by rf-magnetron sputtering using stoichiometric single target were annealed under oxygen atmosphere at $880^{\circ}C$ for 1 hr. The microstructure and superconducting properties of YBCO thin films depended on the composition of pre-annealed thin films. Basal planesuperconducting particles grown on MgO(100) substrate had small and rod-like shade due to preferred orientation, while superconducting film grown on the basal plane-superconducting particles showed round-shape particles. If pre-annealed thin film had nonstoichiometric composition, liquid phase was formed during the heat treatment, which made it easy for particles to grow in the preferred orientation and thus to form textured structure. But the thin films with the textured structure did not show good superconducting properties, especially $T_c$, since the liquid phase transformed into second phase in the grain boundary during the cooling. The effect of the second phase on $T_{c, \;zero}$ was greater than that on $T_{c, \;on}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.288-288
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• 2008

The flux-coupling type superconducting fault current limiter(SFCL) is composed of a series transformer and superconducting unit of the YBCO thin films. The primary and secondary coils in the transformer were wound in series each other through an iron core and the YBCO thin film was connected with secondary coil in parallel. In a normal condition, the flux generated from a primary coil is cancelled out by its structure and the zero resistance of the YBCO thin films. When a fault occurs, the resistance of the YBCO thin films was generated and the fault current was limited by the SFCL. In this paper, we investigated the fault current limiting characteristics according to fault current level in the flux-coupling type SFCL. The experiment results that the fault current limiting characteristics was improved according to increase of the fault current level.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.71-71
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• 2004

• Progress in Superconductivity
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• v.5 no.1
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• pp.80-83
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• 2003

Superconducting YBCO thin films are fabricated on single-crystalline substrates by Metallo-organic Depostion process employing Trifluoroacetic acid as a chelating agent (MOD-TFA). (100)-oriented single crystalline LaAlO$_3$ substrates were employed to grow superconducting film with high crystallinity. The fully processed YBCO thin films were characterized with XRD, SEM, EDS, etc. The microstructures of YBCO thin films show labyrinth-like patterns. The origin of this microstructure was delineated by compositional inhomogeneity during the MOD process and it was shown that the microstructure may be modified by additives. In this work, effects of additives on the microstructures and electrical properties of YBCO thin films have been investigated.