YBa2Cu3O7-x Josephson junctions onbicrystal Al2O3 and SrTiO3 substrates

摘要

Bicrystal grain-boundary junctions (bi-GBJs) have been reproducibly fabricated on SrTiO3 (STO) and r-plane Al2 O3 (sapphire) bicrystal substrates. Sapphire bicrystals are candidates for high-frequency applications due to their low dielectric constant and loss tangent. The sapphire bi-GBJs demonstrated resistively shunted junction (RSJ)-like current voltage characteristics, with junction parameters comparable to the STO bi-GBJs and critical current densities Jc~105 A/cm2. Independent control of junction resistance (RN) was demonstrated with the use of Au shunt layers. In addition, overlayers such as Au or STO may act to passivate the GBJs and improve long term stability