Properties of epitaxial BaTiO₃ deposited on GaAs

Single crystal BaTiO₃ (BTO) has been grown epitaxially on GaAs using molecular beam epitaxy with a 2 unit cell SrTiO₃ nucleation layer. The oxide film is lattice-matched to GaAs through an in-plane rotation of 45° relative to the (100) surface leading to c-axis orientation of the BaTiO₃. X-ray diffraction confirmed the crystallinity and orientation of the oxide film with a full width half maximum of 0.58° for a 7.5 nm thick layer. Piezoresponse force microscopy was used to characterize the ferroelectric domains in the BaTiO₃ layer, and a coercive voltage of 1–2 V and piezoresponse amplitude ∼5 pm/V was measured.