Epitaxial growth of (111) BaTiO 3 thin films on (0002) GaN substrates with SrTiO 3 /TiN buffer layers

High-quality perovskite (111) BaTiO 3 (BTO) ferroelectric thin films were epitaxially grown on wurtzite (0002) GaN substrates with the rationally designed SrTiO 3 (STO)/TiN buffer layers by pulsed laser deposition. Particularly, TiN thin films with excellent conductivity could also be served as the bottom electrodes. The epitaxial relationship of the BTO/STO/TiN/GaN heterostructures was proved to be (111)[1 1̅ 0] BTO//(111)[1 1̅ 0] STO//(111)[1 1̅ 0] TiN//(0002)[11 2̅ 0] GaN by reflection high-energy electron diffraction and high resolution X-ray diffraction. Furthermore, the detailed interface structure and epitaxial relationship of the BTO/STO/TiN/GaN heterostructures were identified on atomic scale by high resolution transmission electron microscopy. The epitaxial (111) BTO ferroelectric thin films on GaN substrates exhibited the favorable ferroelectric properties with the remnant polarization of 12.97 μC cm −2 . The high-quality epitaxial integration of perovskite BTO thin films on wurtzite GaN substrates could promote the potential applications in the advanced GaN-based integrated ferroelectric devices.