Low voltage performance of epitaxial $BiFeO3$ films on Si substrates through lanthanum substitution

We have probed the role of La substitution on the ferroelectric properties of epitaxial $BiFeO3$ films on $SrTiO3$-templated Si. This provides a mechanism to engineer the rhombohedral distortion in the crystal and, thus, control domain structure and switching. With a 10% La substitution, the $(Bi0.9La0.1)FeO3$ film showed well-saturated ferroelectric hysteresis loops with a remanent polarization of $45μC∕cm2$⁠, a converse piezoelectric coefficient $d33$ of $45pm∕V$⁠, and a dielectric constant of 140. Over this range of La substitution, the coercive field systematically decreases such that a coercive voltage of $1V$ can been obtained in a $100nm$ thick film. These results show promise for the ultimate implementation of this lead-free multiferroic operating at voltages in the range of $2–3V$⁠.