CURRENT-VOLTAGE CHARACTERISTICS OF YBA2CU3O7-X THIN-FILMS GROWN IN-SITU BY PULSED-LASER DEPOSITION

High T(c) superconductor YBa2Cu3O7-x thin films have been deposited on SrTiO3(100) and SrTiO3(110) substrates using the pulsed laser deposition technique. X-ray diffraction and pole figure studies reveal that the film deposited on SrTiO3(100) is CoMposed of grains whose c-axes are normal to the substrate so that they form small angle grain boundaries. Most YBa2Cu3O7-x grains grown in the film on SrTiO3(110) have either the (103) or (103 underbar) orientation normal to the substrate, so they form large angle grain boundaries. The different microstructure makes the critical current density of the film on SrTiO3(100) larger than that of the film on SrTiO3(110) by two orders of magnitude. I-V characteristic curves of these films are measured at various temperatures near the critical temperature without an applied magnetic field. The I-V curves for both films follow the scaling behavior of the vortex glass model with critical exponents of z approximately 4.8 and v approximately 1.1.