Epitaxial integration of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (111) thin films on GaN (0002) with La0.5Sr0.5CoO3/TiO2 buffer layers

0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) ferroelectric thin films were epitaxially integrated on GaN (0002) substrates by pulsed laser deposition. La0.5Sr0.5CoO3 (LSCO)/TiO2 buffer layers are designed to decrease the lattice mismatch between PMN-PT and GaN, which promotes the epitaxial growth of pure perovskite PMN-PT (111) thin films. Meanwhile, LSCO/TiO2 heterostructures could be served as the bottom electrodes for integrated ferroelectric devices. Epitaxial relationship of the multilayer is determined to be (111)[11¯0] PMN-PT//(111)[11¯0] LSCO//(100)[001] TiO2//(0002)[112¯0] GaN. The integrated PMN-PT (111) films exhibit good ferroelectric and dielectric properties with remanent polarization of 11.3 μC/cm2, coercive field of 34.1 kV/cm at 100 Hz, dielectric constant of 2035 and dielectric tunability of 68.1% at 1 kHz, which make it a potential candidate for the applications in GaN-based integrated ferroelectric devices.