Thin films of Y-Ba-Cu-O by rf sputtering and study of Josephson effect

Abstract

Thin films of Y-Ba Cu-O material have been prepared by rf diode sputtering using a single oxide target on strontium titanate substrates kept at an ambient temperature. It was found difficult to attain stoichiometry of the films identical to that of the target due to resputtering of the films. The influence of sputtering parameters such as target-substrate distance, rf power, gas pressure and substrate temperature in attaining a particular stoichiometry of the film has been studied. The I-V characteristics of the bridges show Shapiro steps when the bridges are irradiated with microwave radiations. The thin film bridges have the dimensions larger than coherence length: thus all the Josephson effect features are understood to arise due to intergranular junctions.

The measurement and impact of negative oxygen ions during reactive sputter deposition

“…In both papers, no real evidence for negative ion bombardment is given, but the authors refer to similarity for YBCO targets with a preferential loss of Ba. Hirata et al [234] illustrates a barium deficiency in barium for YBa [235].…”