High-Tc Y-Ba-Cu-O Thin Films Prepared by Dual Magnetron Sputtering

Abstract

Y-Ba-Cu-O thin films (200-300 nm thick) have been magnetron-sputtered on heated sapphire substrates. By means of dual sputtering configuration with a Cu and sintered Y-Ba-Cu-O target, films having compositions closer to Y₁Ba₂Cu₃O _y are reproducibly obtained at a substrate temperature of about 600°C. They have a nearly single-phase perovskite-like structure with highly c-axis preferred orientation and show a T _c onset of 90 K. Remarkable improvement in the zero resistivity temperature (up to 73 K) is achieved by subsequent annealing of these films at 550-650°C, while annealing at higher temperatures leads to T _c degradation.