Anisotropic electrical properties of epitaxial Hf-doped Bi4Ti3O12 thin films on (100)- and (111)-oriented SrTiO3 substrates

Epitaxial thin films of (001)- and (104)-oriented Bi4Ti3-xHfxO12(BTH) have been fabricated on (100)- and (111)-oriented SrTiO3 substrates with SrRuO3 bottom electrodes by pulsed laser deposition, respectively. X-ray diffraction scans revealed that a unique epitaxial relationship between film and substrate: BTH (001) //SrTiO3 (001); BTH [1-10]// //SrTiO3 [100] is valid for both orientations, irrespective of their orientation. The strong dependences of ferroelectric properties on the film orientation were observed. The remanent polarization 2Pr is 45.6 mu C/cm2 for (104)-oriented BTH film, while 2Pr is 4.5 mu C/cm2 for (001)-oriented BTH film. The anisotropic properties of BTH are similar to that of pure Bi4Ti3O12(BIT): the polarization vector of BTH films is close to the a axis, indicating that Hf substitution does not change the orientation dependence of electric properties in BIT. (c) 2012 Published by Elsevier B.V. Selection and/or peer review under responsibility of Chinese Vacuum Society (CVS).