Aging of superconducting Y1Ba2Cu3O7−x structures on silicon

The long-term stability of epitaxial thin film structures of superconducting Y1Ba2Cu3O7−x on silicon wafers (100), using a yttria-stabilized ZrO2(YSZ) buffer, is presented and compared to identical structures on SrTiO3 (100) and yttria-stabilized ZrO2 (100) single crystals. For Y1Ba2Cu3O7−y/YSZ/Si heterostructures, the maximum Y1Ba2Cu3O7−y film thickness is limited to 50 nm; otherwise thermal strain induces microcracks. Thinner films are more stable, but nevertheless show aging over several weeks, which affects critical current density and room-temperature resistivity, but not the critical temperature Tc.