In applications of superconducting devices, the crystalline texture of high-quality YBa 2 Cu 3 O 7−x thin films is of primary importance. The preferred orientation of the films can be essentially controlled by means of the substrate temperature, T s . In order to study the dependence of the film texture on different T s , a series of films were deposited on YSZ substrates by the on-axis pulsed-laser ablation technique. The substrate temperature was varied from 600 • C to 800 • C while the rest of the growth parameters remained the same. Various analytical techniques, including x-ray diffraction, scanning electron microscopy, micro-Raman spectroscopy and the four-point probe method, were applied to characterize the films. At around T s = 700 • C, the best films with the smoothest surface morphology, lowest FWHM of the rocking curve and highest in-plane texture were obtained. The resultant J c in excess of 1 × 10 6 A cm −2 at 77 K and T c around 91 K were also achieved at this temperature.

Micro-Raman spectroscopy has been used to analyse the substrate temperature effects on high temperature superconducting YBa2Cu3O7-x thin films grown by the in situ pulsed laser deposition method. In particular, the dependence of the epitaxy quality on substrate temperature Ts is studied. Our results reveal that films with the highest epitaxy degree are grown with substrate temperature Ts between 680 and 720 °C, in good agreement with previous superconducting transition temperature measurements and x-ray diffraction analyses. In addition, the formation and distribution of impurities produced during growth are identified by Raman spectra and Raman imaging, and they are found to be more pronounced at higher substrate temperatures. Finally, localized Raman analysis has been performed to investigate the orientation of the single crystal grains in films grown at substrate temperature Ts>760 °C. It is confirmed that, within the experimental error of 3°, the crystal a/b-axes of these single crystal grains have a strong tendency to orient themselves along the crystal axis of the substrate, independent of their size, shape and orientation of the domain boundaries.