Epitaxial Growth of MgO Layer on Y₁Ba₂Cu₃O_7-y Thin Film

Abstract

A MgO/Y 1 Ba 2 Cu 3 O 7- y (YBCO) structure on a MgO(100) substrate was prepared by a reactive vacuum evaporation method. The MgO layer with (100) orientation was obtained on each of the (001) and (100) YBCO thin films at the substrate temperature of 400°C. The crystallinity of the MgO layer as a function of the MgO thickness was investigated. The randomness of the crystallinity became smaller with a decrease in the thickness. The (100) epitaxial MgO layer without other orientations was obtained at a thickness of 5 nm. Structures of both YBCO/MgO/YBCO(001) and YBCO/MgO/YBCO(100) were studied. From the result of the cross-sectional TEM observation, it was confirmed that for both the (001) and (100) base YBCO layers, top YBCO layers with the same orientation were epitaxially grown via the intermediate MgO layer with a thickness of 5 nm.