Strain-driven domain structure control and ferroelectric properties of BaTiO3 thin films

We have studied the domain structure formation in annealed BaTiO3 films grown on SrTiO3. We show that it is possible to utilize the 2.28% lattice mismatch strain at the SrTiO3/BaTiO3 interface to obtain uniaxially c-axis-oriented BaTiO3 films with a thickness of up to about 200 nm. This thickness is much larger than the typical critical thickness for BaTiO3 films on SrTiO3 and such films therefore can potentially be useful for optical waveguide applications. We also looked at the polarization properties of the uniaxial BaTiO3 films. Our measurements and analysis indicate that the heavily distorted interface region, with a thickness of approximately 2 nm is non-ferroelectric.