Prospects and Problems in Fabrication of MgB2 Josephson Junctions

Abstract

We briefly survey recent developments in the thin film synthesis and junction fabrication of MgB 2 toward superconducting electronics. The most serious problem in the thin film synthesis of MgB 2 is the high vapor pressure required for phase stability. This problem makes insitu film growth difficult. However, there has been substantial progress in thin film technology for MgB 2 in the past three years. The low-temperature thin-film process in a UHV chamber can produce high-quality MgB 2 films with T c ∼ 35 K. Furthermore, technology to produce single-crystal epitaxial MgB 2 films has recently been developed by using hybrid physical-chemical vapor deposition. With regard to Josephson junctions, various types of junctions have been fabricated, all of which indicate that MgB 2 has potential for superconducting devices that operate at 20-30 K, the temperature reached by current commercial cryocoolers.