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.