Orientation control of epitaxial tetragonal Pb(ZrxTi1−x)O3 thin films grown on (100)KTaO3 substrates by tuning the Zr/(Zr + Ti) ratio

Pulsed metal organic chemical vapor deposition is used to epitaxially grow 30-nm thick tetragonal Pb(ZrxTi1−x)O3 thin films on (100) KTaO3 single crystal substrates. The in-plane misfit strain, which is controlled by the Zr/(Zr+Ti) ratio of Pb(ZrxTi1−x)O3 thin films, tunes the film orientation. When Zr/(Zr+Ti) = 0, which leads to the tensile strain from the substrate, a perfectly (100)-oriented film is formed, whereas when Zr/(Zr+Ti) = 0.45, which leads to the compressive strain from the substrate, a completely (001)-oriented film is realized. The volume fraction of the (001)-oriented domain almost linearly increases as the Zr/(Zr+Ti) ratio increases for films with (100) and (001) mixed orientations; this change in the volume fraction can be explained by considering the average lattice parameter matching between the Pb(ZrxTi1−x)O3 thin film and the KTaO3 substrate. These results demonstrate a method to systematically control the film orientation using the Zr/(Zr+Ti) ratio to tune the in-plane strain of Pb(ZrxTi1−x)O3 films grown on (100) KTaO3 single crystal substrates.