THE EFFECTS OF ADDED GASES IN THE SPUTTER DEPOSITION OF YBa2Cu3O7 THIN FILMS

YBa2Cu3O7 thin films have been deposited on MgO substrates by off-axis magnetron sputtering in argon, oxygen, and an additional gas. Additions of nitrogen, hydrogen, methane, air, and water vapor in amounts of up to 25% were used in this investigation. Each gas stabilized the target voltage and growth rate for the duration of the deposition. Growth rates improved by over 50% with as little as 3% hydrogen. When used with a target which had degraded after more than 150 hours use, the added gas improved T-C and J(C) beyond levels attained from the new target. T-c increased from 82 K without hydrogen to 89 K with hydrogen and J(C)(12K) from 3x10(4) to >7x10(6) A/cm(2). Nitrogen yielded less dramatic effects. We attribute these improvements to the catalytic effect of these gases in maintaining elevated levels of atomic oxygen during film growth.