Role of buffer layers for superconducting YBa2Cu3O7−x thin films on GaAs substrates

Abstract
High‐temperature superconducting YBa2Cu3O7−x (YBCO) thin films were deposited on GaAs substrates by laser ablation. A double‐buffer layer of yttrium‐stabilized ZrO2 (YSZ)/Si3N4 was used to nucleate YBCO but also to prevent the degradation of the GaAs during YBCO film deposition. Superconducting YBCO thin films with a highly c‐axis orientation perpendicular to the substrate surface, zero‐resistance temperature of 85.5 K, and critical current density of 1.9×103 and 1.3×104 A/cm2 at 77 and 50 K, respectively, have been achieved in our experiments. These values are believed to be the best results reported so far for YBCO on GaAs.