Epitaxial growth of perovskite (111) 0.65PMN-0.35PT films directly on wurtzite GaN (0002) surface

PMN-PT films were deposited on GaN/sapphire substrates via pulsed laser deposition without any intermediate buffer layers, and epitaxial perovskite (111) 0.65PMN-0.35PT films on wurtzite GaN(0002) surfaces were obtained by adjusting the experimental parameters including substrates temperature and O _2 pressure. The microstructures and electrical properties of PMN-PT/GaN heterostructure were characterized by reflection high-energy electron diffraction, X-ray diffraction, atom force microscope, transmission electron microscope and polarization–electric field (P–E) measurements. The as-grown PMN-PT films exhibit highly (111) oriented perovskite crystal structure. The in-plane orientation relationship of PMN-PT film with respect to GaN is (111) × [11-2] PMN-PT//(0002) × [11-20] GaN. A domain matching epitaxy model is proposed to account for the epitaxial growth mechanism of PMN-PT on GaN. The P–E curves show typical ferroelectric characteristics, while the remnant polarization and coercive field are about 18.1 C/cm ^2 and 75 kV/cm, respectively. This work provides a good start point for the further development of advanced electronic devices based on the integration of ferroelectric PMN-PT with wide-gap GaN semiconductor.