YBa2Cu3O7−x films on off-axis Y-ZrO2 substrates using Y-ZrO2 or Y2O3 barrier layers

Abstract

YBa2Cu3O7−x (YBCO) and barrier layer films were deposited on single-crystal (Y2O3)0.09(ZrO2)0.91 substrates cut between 3.6 and 35.7°off-axis from the (001) planes. The barrier layers were (Y2O3)0.065(Y-ZrO2)0.935(Y-ZrO2), Y2O3, or multilayered structures of Y-ZrO2 and Y2O3. X-ray diffraction showed that the Y-ZrO2 and Y2O3 barrier layers generally grew epitaxially on the off-axis substrates, with the (001) barrier layer film planes being parallel to those of the substrate, and the (100) directions being parallel. YBCO films deposited on Y2O3 barrier layers also showed epitaxy with the YBCO (001) planes being nearly parallel to the substrate (001) planes, even for miscuts up to 35.7°. In contrast, the (001) planes of YBCO films deposited on Y-ZrO2 barrier layers were almost parallel to the substrate surface, not the (001) substrate planes. However, YBCO films on Y-ZrO2 films maintained particular in-plane epitaxial orientations with respect to the substrate. The YBCO full-width at half-maximum (FWHM) x-ray peaks were slightly narrower (0.8°) on Y2O3 barrier layers than on Y-ZrO2 layers (1.3°). The electrical resistivity versus temperature behavior of the YBCO/Y2O3 films was consistent with increased grain boundary scattering as the degree of substrate miscut increased, whereas YBCO/Y-ZrO2 films' resistivities showed less sensitivity to substrate miscut, consistent with the loss of epitaxy.