Orientation dependence of ferroelectricity of epitaxially grown Pb(ZrxTi1−x)O3 thin films prepared by metalorganic chemical vapor deposition

Epitaxial Pb(ZrxTi1−x)O3 films with (001) and (100), (101) and (110), and (111) orientations were grown on (100)SrRuO3//(100)SrTiO3, (110)SrRuO3//(110)SrTiO3, and (111)SrRuO3//(111)SrTiO3 substrates, respectively. The two composition films with Zr/(Zr+Ti) ratios of 0.42 and 0.68 were prepared with the Pb/(Pb+Zr+Ti) ratio of 0.5. Well saturated and good square shape hysteresis loops with large remanent polarization (Pr) above 40 μC/cm2 were observed for all films. The Pr increased in the following order: (101), (111), and (001) orientations for the film with the Zr/(Zr+Ti) ratio of 0.42 and (100), (110), and (111) orientations for the Zr/(Zr+Ti) ratio of 0.68. On the other hand, the Ec value mainly depended on the Zr/(Zr+Ti) ratio and not on the orientation of the film; the Ec value of the film with a Zr/(Zr+Ti) ratio of 0.42 was larger than that of 0.68. The saturation behavior did not strongly depend on the orientation, especially for the films with the Zr/(Zr+Ti) ratio of 0.42. The frequency dependence of the dielectric constant was small regardless of the orientation of the films with a Zr/(Zr+Ti) ratio of 0.42. On the other hand, for 0.68, it was also small for the (100) and (110) orientations, but increased by about 15% from 103 to 106 Hz for the (111) orientation due to the relative large leakage. The (101)-oriented film with the Zr/(Zr+Ti) ratio of 0.42 and the (100)- and (111)-oriented films with 0.68 did not show deterioration up to 1010 switching cycles.