• Korean Journal of Materials Research
• /
• v.1 no.2
• /
• pp.93-98
• /
• 1991

The as-grown $YBa_2Cu_3O_{7-x}$ superconducting thin films on MgO(100) substrate have been prepared by a reactive coevaporation method. The superconducting transition temperature, surface morphology and crystalline quality were examined as a function of the substrate temperature ranging from $450^{\circ}C$ to $590^{\circ}C$. From the reflection high energy electron diffraction (RHEED) analysis, it was found the film consisted of almost amorphous phase with a halo pattern deposited at the substrate temperature of $450^{\circ}C$. The film deposited at the substrate temperature of $510^{\circ}C$ consisted of polycrystalline phase, showing a broad ring pattern. On the other hand, for the film deposited at $590^{\circ}C$, RHEED showed spotty pattern indicating that this film consisted of single crystal phase. It has rough film surface due to the surface outgrowth. The surface outgrowth increased as the substrate temperature increased from $510^{\circ}C$ to $590^{\circ}C$. the surface outgrowth may be due to the anisotropic growth rate. The highest transition temperature obtained in this study was $Tc_{zero}$ of 83K with $Tc_{onset}$ of 88K for the film deposited at $590^{\circ}C$ using activated RF oxygen plasma.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.02a
• /
• pp.287-290
• /
• 2003

For microwave device applications, c-axis oriented high temperature superconducting YBa$_2$Cu$_3$O$_{7-{\delta}}$ (HTS-YBCO) epitaxial thin films on the r-cut sapphire substrate(Al$_2$O$_3$) were prepared. In order to reduce the lattice mismatch with a substrate and to enhance the crystallity of HTS thin films, CeO$_2$ buffer layer on the r-cut sapphire substrate was grown by the RF-magnetron sputtering. The YBCO films on the CeO$_2$ buffer layer were deposited using the pulsed-laser deposition (PLD) method. These HTS YBCO /CeO$_2$/Al$_2$O$_3$ multilayer thin films(30 $\times$ 30 mm$^2$) routinely exhibited a critical temperature(T$_{c}$) of 89 K from the R-T measurement. Using HTS YBCO/CeO$_2$ /Al$_2$O$_3$ multilayer thin film. We fabricated and characterized the microwave passive devices (planar type filters) with cryopack-age such as the coupled -line type low-pass filter (LPF) and the open-loop meander type bandpass filter (BPF).filter (BPF).).

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1993.11a
• /
• pp.5-6
• /
• 1993

• 한국초전도학회:학술대회논문집
• /
• 2009.07a
• /
• pp.29-29
• /
• 2009

• Proceedings of the Korean Vacuum Society Conference
• /
• 2008.02a
• /
• pp.153-153
• /
• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05d
• /
• pp.45-48
• /
• 2003

BiSrCaCuO thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

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

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.10a
• /
• pp.40-44
• /
• 2000

$Bi_2Sr_2Ca_nCu_{n+1}O_y$($n{\geq}0$; BSCCO)thin film is fabricated via two different processes using an ion beam sputtering method i.e. co-deposition and layer-by-layer deposition. A single phase of Bi2212 can be fabricated via the co-deposition process. While it cannot be obtained by the layer-by-layer process. Ultra-low growth rate in our ion beam sputtering system brings out the difference in Bi element adsorption between the two processes and results in only 30% adsorption against total incident Bi amount by layer-by-layer deposition, in contrast to enough Bi adsorption by co-deposition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.9
• /
• pp.796-800
• /
• 2000

Bi$_2$Sr$_2$Ca$_{n}$Cu$_{n+1}$ O$_{y}$(n$\geq$0; BSCCO) thin film is fabricated via two different processes using an ion beam sputtering method i.e. co-deposition and layer-by-layer deposition. A single phase of Bi2212 can be fabricated via the co-deposition process. While it cannot be obtained by the layer-by-layer process. Ultra-low growth rate in our ion beam sputtering system brings out the difference in Bi element adsorption between the two processes and results in only 30% adsorption against total incident Bi amount by layer-by-layer deposition, in contrast to enough Bi adsorption by co-deposition.on.n.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.929-931
• /
• 1999

BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, ozone gas pressure dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.