Domain structure of epitaxial PbTiO₃ films grown on vicinal (001) SrTiO₃

Epitaxial PbTiO₃ films have been grown on vicinal (001) SrTiO₃ substrates by pulsed laser deposition. Vicinal SrTiO₃ substrates with misorientations up to 9° from (001) were used, and the influence of the direction of misorientation on the resulting domain structure was studied. 4-circle x-ray diffraction analysis indicates that thin (40 nm) PbTiO₃ films are completely c-axis oriented [rocking curve full-width-at-half-maximum (FWHM) of 0.25° for the 002 reflection] and that thicker films (∼ 200 nm) contain mixed a-axis and c-axis PbTiO₃ domains due to twinning along {011} planes. The [100] axis of the a-axis domains is misoriented by 2.1° to 3.3° toward 〈100〉 substrate directions with respect to the substrate normal. In contrast to growth on well-oriented (001) SrTiO₃ surfaces where the four equivalent tilts of the [100] axis of the a-axis domains are equally likely, on vicinal SrTiO₃ the a-axis domains are preferentially oriented in an uphill direction with respect to the crystallographic miscut.