Analysis of grain orientation and intergrain properties by micro-Raman spectroscopy in YBa₂Cu₃O_7–x thin films

Superconducting YBa2Cu3O7-x (YBCO) thin films grown by pulser-laser-assisted deposition were studied by micro-Raman spectroscopy. This technique was used to estimate the epitaxial quality of the films in terms of the presence of c-axis- and a-axis-oriented areas. The advantage of micro-Raman spectroscopy is its high lateral resolution, and this was used to study the homogeneity of the films at submicrometric level. Local structural changes from a large number of intergrain regions were revealed by changes of the Raman parameters. For example, the aggregation of a-axis-oriented grains formed needle-shaped macrograins. Micro-Raman measurements suggest that these grains were seeded at large-angle grain boundaries in c-axis-oriented areas.