Self-assembled stoichiometric barium titanate thin films grown by molecular beam epitaxy

The growth of stoichiometric barium titanate using molecular beam epitaxy was investigated by providing excess barium during co-deposition of barium, titanium, and oxygen. X-ray photoelectron spectroscopy confirmed that excess barium accumulated at the surface as barium oxide, and that post methanol cleaning removed the barium oxide and resulted in the stoichiometry of all grown films to be that of bulk stoichiometric barium titanate. Piezoforce microscopy was used to determine the ferroelectric properties of the thin films. Results demonstrated the d33 values were equal to or better than bulk values. These results indicate that the excess barium self-limited the growth to the stoichiometry of barium titanate by transferring the excess barium to the surface as barium oxide, creating a new growth approach for barium titanate.