A-axis YBCO thin films deposited by DC magnetron sputtering

Abstract

A-axis YBCO thin films deposited on SrTiO3 and MgO substrates were prepared using the template-layer method by off-axis magnetron sputtering. The thin films deposited on MgO with template layers displayed better electrical properties and crystallinity than those deposited on the substrates without template layers, whereas the crystallinity of films deposited on SrTiO3 by the template-layer method showed no improvement. The surface morphology of the films, observed by high-resolution scanning electron microscopy, indicates that the homoepitaxial growth of the a-axis films on template layers on MgO and SrTiO3 results in rougher surfaces than in the case of heteroepitaxial growth of template layers. The possible mechanisms contributing to these differences in surface roughness were carefully investigated. Atomic force microscopy was also used to characterize the initial growth of a-axis films on MgO and SrTiO3. According to the results, the initial growth of a-axis films on MgO and SrTiO3 resembles that of island growth.