Towards the development of YBa₂Cu₃O₇-based S-I-S tunneling Josephson junction device

Josephson junctions are used to fabricate superconductor quantum interference devices (SQUIDs), qubits, and terahertz frequency devices. YBa₂Cu₃O₇ (YBCO)-based S-I-S tunneling Josephson junctions offer many advantages over the conventional low temperature superconductor-based Josephson junctions including low cost, cryogenic system simplicity, and high I_cR_n product value (with I_c being the junction critical current and R_n the normal resistance). However, the development of a well-controlled and reproducible YBCO based S-I-S tunneling Josephson junction is very challenging since the thickness of the electrical insulation layer (I) on the junction has to be only about a nanometer and it must provide a very high potential barrier in the junction.

Here, we present our work towards the development of the YBCO based S-I-S tunneling Josephson junction device by discussing growth, structure, and electrical transport properties of (110)-YBCO, various metals (M) doped PrBa₂(Cu_0.8M_0.2)₃O₇ (PBCMO)_, and heterostructures of YBCO and PBCMO_. In particular, we discuss thin film deposition of (110)-oriented YBCO, PBCMO, and heterostructures of YBCO and PBCMO and their electrical transport properties including the electrical resistivity, conduction mechanism, and proximity effects.