Enhancement of piezoelectric properties of (100)-orientated BiFeO_3 films on (100)LaNiO_3/Si

摘要

The piezoelectric properties of (100)-orientated BiFeO_3 thin films grown on (100)LaNiO_3/SiO_2/(100)Si were investigated. 200-nm-thick LaNiO_3 and 250-nm-thick BiFeO_3 was deposited by the rf magnetron sputtering method and sol-gel method, respectively. The (100)-oriented BiFeO_3 films were distorted to the in-plane tensile direction owing to the low thermal expansion coefficient of the Si substrate. While no significant dependence of the in-plane lattice distortion on the dielectric and ferroelectric properties and d_(33,AFM) piezoelectric coefficient measured by scanning probe microscopy was observed, it was found that the e_(31,f) piezoelectric coefficient increases with increasing the lattice distortion. The maximum e_(31,f) and figure of merit (FOM) were -4.0 C/m and 14 GPa, respectively, which are comparable to those of epitaxially grown (100)BiFeO_3 films.