• Progress in Superconductivity and Cryogenics
• /
• v.6 no.3
• /
• pp.16-20
• /
• 2004

YB $a_2$C $u_3$$O_{7-x}$ (YBCO) films were deposited on (100) SrTi $O_3$ single crystal substrates by a metal organic chemical vapor deposition (MOCVD) system of hot-wall type using single liquid source. Under the condition of the mole ratio of Y(tmhd)$_3$:Ba(tmhd)$_2$:Cu(tmhd)$_2$= 1:2.1:2.9. the deposition pressure of 10 Torr. the MO source line speed of 15 cm/min. the Ar/ $O_2$ flow rate of 800/800 sccm. YBCO films were prepared at the deposition temperatures of 780∼89$0^{\circ}C$. In case of the YBCO films with 2.2 ${\mu}{\textrm}{m}$ thickness deposited for 6 minutes at 86$0^{\circ}C$. XRD pattern showed complete c-axis growth and SEM morphology showed dense and crack-free surface. The atomic ratios of Ba/Y and Cu/Ba in the film were 1.92 and 1.56. respectively. The deposition rate of the film was as high as 0.37 ${\mu}{\textrm}{m}$/min. The critical temperature ( $T_{c.zero}$) of the film was 87K. The critical current of the film was 104 A/cm-width. and the critical current density was 0.47 MA/$\textrm{cm}^2$. For the thinner film of 1.3 ${\mu}{\textrm}{m}$ thickness. the critical current density of 0.62 MA/$\textrm{cm}^2$ was obtained.d.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.10a
• /
• pp.83-86
• /
• 2003

YBa$_2$Cu$_3$$O_{7-x}$ thin films for coated conductor application were deposited on a MgO single crystalline substrate by a metal organic chemical vapor deposition (MOCVD) system of a vertical type using a single liquid source. The film uniformity was enhanced by controlling the gas shower head structure, the distance between the shower head and substrate, and the rotation of the substrate. The source mole ratio of Y(thd)$_3$: Ba(thd)$_2$: Cu(thd)$_2$ was changed for obtaining stoichiometric film. The phase formation, crystal orientation, surface morphology and film composition were investigated with different source mole ratios, and the critical temperature (T$_{c}$) was measured.red.

• Progress in Superconductivity and Cryogenics
• /
• v.6 no.3
• /
• pp.21-26
• /
• 2004

Deposition condition of YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) films on moving IBAD templates (CeO$_2$/IBAD-YSZ/SS) was studied in a hot-wall type metal organic chemical vapor deposition (MOCVD) process using single liquid source. The reel velocity was 40 cm/hr and the source mole ratios of Y(tmhd)$_3$:Ba(tmhd)$_2$:Cu(tmhd)$_2$ were 1:2.3:3.1 and 1:2.1:2,9, Two different types of IBAD templates with thin CeO$_2$ and thick CeO$_2$ layers were used, The YBCO films were successfully deposited at the deposition temperatures of 780~89$0^{\circ}C$ ; the a-axis growth was observed together with the c-axis growth up to 83$0^{\circ}C$. while the c-axis growth became dominant above 83$0^{\circ}C$. The top surface of the c-axis film was fairly dense and included a small amount of the a-axis growth, although the peaks of the a-axis grains were not observed in XRD pattern, The YBCO film deposited on IBAD template with thin CeO$_2$ layer showed low critical current of 2.5 A/cm-width. while the YBCO film deposited on IBAD template with thick CeO$_2$ layer showed higher critical current of 50 A/cm-width. This result indicates that thick CeO$_2$ layer is thermally more stable than thin CeO$_2$ layer at the high deposition temperature of the MOCVD process.s.

• Progress in Superconductivity
• /
• v.7 no.1
• /
• pp.69-76
• /
• 2005

Complex single buffer composed of yttrium and samarium oxide was deposited on the metallic substrates by MOCVD (metal organic chemical vapor deposition) method using single liquid source. Two different types of the substrates with in-plane textures of about $8{\sim}10$ degree of Ni and $3at.\%W-Ni$ alloy were used. Y(tmhd: 2,2,6,6-tetramethyl-3,5-heptane dionate)$_3$:Sm(tmhd)$_3$ of liquid source was adjusted to 0.4:0.6 to minimize the lattice mismatch between the complex single buffer and the YBCO. The epitaxial growth of $(Y_{x}Sm_{1-x})_{2}O_3$ was achieved at the temperature higher than $500^{\circ}C$ in $O_2$ atmosphere. However, it was found that the formation of NiO accelerated with increasing deposition temperature. By supplying $H_{2}O$ vapor, this oxidation of the substrate could be suppressed throughout the deposition temperatures. We could get the epitaxial growth on pure Ni substrate without the formation of NiO. The competitive (222) and (400) growths were observed at the deposition temperatures of $650\~750^{\circ}C$, but the (400) growth became dominant above $800^{\circ}C$. The $(Y_{x}Sm_{1-x})_{2}O_3$-buffered metallic substrates can be used as the buffer for YBCO coated conductor.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.129-132
• /
• 1999

A new single solution source MOCVD technique for the deposition of YBCO film has been developed, using a ultrasonic atomizer to feed the precursors into an evaporation zone. This method being investigated as a basis for future long wire fabrication, for example the electric power use, the magnatic applications, etc.. YBCO films were prepared on MgO(100) substrate, using mixture of Y, Ba, and Cu ${\beta}$ -diketonate chelate was dissolve in tetrahydrofuran as a solution sources. X-ray diffraction measurement indicated that the thin film grew epitaxially with the c-axis orientation perpandicular to the surface of the surface.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.02a
• /
• pp.129-132
• /
• 2003

Yttria stabilized zirconia (YSZ) buffer layers were deposited by a metal organic chemical vapor deposition (MOCVD) technique using single liquid source for the application of YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) coated conductor. Y:Zr mole ratio was 0.2:0.8, and tetrahydrofuran (THF) was used as a solvent. The (100) single crystal MgO substrate was used for searching deposition condition. Bi-axially oriented CeO$_2$ and NiO films were fabricated on {100}〈001〉 Ni substrate by the same method and used as templates. At a constant working pressure of 10 Torr, the deposition temperatures (660~80$0^{\circ}C$) and oxygen flow rates (100~500 sccm) were changed to find the optimum deposition condition. The best (100) oriented YSZ film on MgO was obtained at 74$0^{\circ}C$ and $O_2$ flow rate of 300 sccm. For YSZ buffer layer with this deposition condition on CeO$_2$/Ni template, full width half maximum (FWHM) values of the in-plane and out-of-plane alignments were 10.6$^{\circ}$ and 9.8$^{\circ}$, respectively. The SEM image of YSZ film on CeO$_2$/Ni showed surface morphologies without microcrack.k.