$YBa_2Cu_3O_{7-X}$ high temperature superconducting thin films were deposited with Metal Organic Chemical Vapor Deposition (MOCVD) method. Source materials were Y(thd)3, Ba(thd)2, Cu(thd)2 and their evaporation characteristics were investigated. Only the Ba(thd)2 source showed the degradation of evaporation characteristics after 30 minutes.
The $YBa_2Cu_3O_{7-X}$ thin films were deposited on the $LaAlO_3$ (100), Mgo (100) single crystal substrate. Effect of deposition temperature on the microstructure of thin film was studied. At the higher deposition temperature, 870℃, the grain size was larger than 1μm and the grain growth direction was c-axis normal to the surface of the substrate. At the lower deposition temperature, 810℃, the grain size was about 1μm and the grain growth direction was a,b-axis normal to the surface of the substrate. Effect of deposition pressure on the microstructure of thin film was studied. As the deposition pressure changed from 5.5 torr to 4.5 torr, at the deposition temperature of 830℃, grain growth direction changed from c-axis normal a,b-axis normal to the surface of the substrate. But the grain size did not changed, and it was about 1μm.
Microbridge type Josephson junctions were fabricated with $YBa_2Cu_3O_{7-X}$ high temperature superconducting thin films, which have various microstructure. Microbridges made of $YBa_2Cu_3O_{7-X}$ thin films on MgO substrate showed RSJ like I-V characteristics. Microbridges made of a,b-axis normal $YBa_2Cu_3O_{7-X}$ thin films on LaAlO substrate showed RSJ like I-V characteristics, but that of the c-axis normal films showed flux flow type I-V characteristics. The (102) pole $\varphi$-scan result of c-axis normal $YBa_2Cu_3O_{7-X}$ thin films on MgO substrate showed 45° spacing, which means that the grains on MgO substrate formed high angle grain boundary. But that on $LaAlO_3$ substrate showed 90 spacing which means that c-axis normal $YBa_2Cu_3O_{7-X}$ thin films on LaAlO substrate have epitaxial growth. In conclusion, for fabrication of microbridge type Josephson junction, $YBa_2Cu_3O_{7-X}$ thin films with high angle grain boundary is needed.
Microstrip line half wavelength resonator was fabricated with $YBa_2Cu_3O_{7-X}$ high temperature superconducting thin films and with Cu thin films. Quality factor and insertion loss of the resonators were measured with network analyser, and the surface resistance of the thin films were calculated. Surface resistance of the Cu films were high than that of $YBa_2Cu_3O_{7-X}$ thin films on MgO and $LaAlO_3$ substrate. Surface resistance of the c-axis normal $YBa_2Cu_3O_{7-X}$ thin films were lower than that of a,b-axis noraml $YBa_2Cu_3O_{7-X}$ thin films. Lowest surface resistance value was obtained from c-axis normal $YBa_2Cu_3O_{7-X}$ thin films on $LaAlO_3$ substrate, which showed epitaxial grain growth. For the application of $YBa_2Cu_3O_{7-X} high temperature superconducting thin films on microstrip line microwave passive device, c-axis normal, epitaxial films were preferred.
