MORPHOLOGY AND TRANSPORT OF YBA2CU3O7-X SPUTTERED IN ARGON, OXYGEN, AND HYDROGEN - DEPENDENCE ON DEPOSITION TEMPERATURE

YBa2Cu3O7-x films have been deposited on MgO by reactive, off-axis magnetron sputtering in an argon, oxygen, and hydrogen gas mixture. The material and electrical properties of the films were studied for deposition temperatures from 600 to 760-degrees-C. The films, all approximately 300 nm thick, were predominantly a-axis oriented when deposited at or below 620-degrees-C but were c-axis oriented when deposited at temperatures above 640-degrees-C. The surfaces of films deposited between 640 and 710-degrees-C were partially covered with a-axis grains. Surface roughness measurements indicated the smoothest films occurred for deposition temperatures below 680-degrees-C. Resistance ratios as great as 3.1 were observed for some films. Transition temperatures exceeded 89 K and resistivities at 100 K were less than 150 muOMEGA cm for the best films. Low-temperature critical current densities exceeded 10(7) A/cm2 for films deposited from 640 to 720-degrees-C. The temperature dependence of the critical current density near the transition temperature had a power law dependence of nearly 3/2 for deposition temperatures below 690-degrees-C. The power law dependence decreased for increasing deposition temperatures, dropping to nearly 1.1 in the film deposited at 750-degrees-C.