YBa2Cu3O7‐δ Films on GaAs with High Critical Current Densities.

Abstract Epitaxial YBa 2 Cu 3 O 7−δ films were grown on GaAs substrates using an intermediate MgO buffer layer. It turned out that the basic requirements in coping with GaAs related problems such as chemical instability and volatility are lowest possible deposition temperatures and proper encapsulation of bare GaAs faces, respectively. Applying our coevaporation technique we were able to achieve YBa 2 Cu 3 O 7−δ films on GaAs which can compete with those on standard substrates ( T c = 87 K , ρ(100 K) = 40μΩ cm, j c = 2 ·10 6 A/cm 2 at 77 K ).