Role of buffer layers for superconducting YBa₂Cu ₃O_7-x thin films on GaAs substrates

High-temperature superconducting YBa₂Cu₃O _7-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.