Piezoelectric properties of (100) orientated BiFeO3 thin films on LaNiO3

To improve the piezoelectric properties of sol-gel-derived BiFeO3 films for MEMS application, (100) oriented films were prepared by using LaNiO3 bottom electrodes, which have preferential (100) orientation on Si substrates. The microstructure of the films crystalized at 450 and 500 degrees C was a layered granular structure and that crystalized at 550 and 600 degrees C changed to a columnar structure. The increase in the domain size with increasing the annealing temperature was also observed by piezoelectric force microscopy. Most of the film characteristics including the dielectric constant, remanent polarization, and d(33),(AFM) coefficient were enhanced gradually with increasing annealing temperature. In contrast, the e(31,f) coefficient showed a much larger increase than the others, which suggests that the e(31,f) coefficient is strongly influenced by the domain size. The largest e(31,f) coefficient of the (100) BiFeO3 films was -4.1C/m(2), which is about 4 times larger than that of the polycrystalline films. (C) 2014 The Japan Society of Applied Physics