As-deposited superconducting Y-Ba-Cu-O thin films on Si, Al2O3, and SrTiO3 substrates

Abstract

We have developed an electron beam evaporator designed to deal with the special requirements of thin films of oxide superconductors. The growing surface is sprayed with plasma‐excited oxygen while the sources and rate monitors operate in a low background pressure. This allows us to reproducibly grow films of Y‐Ba‐Cu‐O on Si, Al₂O₃, and SrTiO₃ substrates at a substrate temperature of 540 °C which are superconducting without the need for annealing. The resistive transitions of most films show an onset of 90 K and zero resistance by 68 K. X‐ray diffraction indicates a preferred orientation for growth on most Si and SrTiO₃ substrates. A preliminary measurement yields critical currents of at least 10⁴ A/cm² at 4.2 K for a film on silicon.