Epitaxial Growth and Ferroelectricity of BaTiO3 on SrRuO3/TiO2 Buffered GaN

Epitaxial growth of (111)-oriented BaTiO3 thin films on GaN/Al2O3 (0001) substrates has been realized by intervening epitaxial (111) SrRuO3/(100)TiO2 buffer layers. Rutile TiO2 was deposited by Laser molecular beam epitaxial firstly and the deposition process of TiO2 layer was in-situ monitored by reflective high energy electron diffractions. After that SrRuO3 conductive films and BaTiO3 ferroelectric films were fabricated via pulsed laser deposition. The perovskite BaTiO3 films were epitaxially grown on wurtzite GaN as revealed by X-ray diffraction. Electrical measurements demonstrate that the BaTiO3 films possess a saturation ferroelectric hysteresis loop, butterfly-shape C-V curve and low leakage current density. These results show that BaTiO3 films with favorable electrical performance could be epitaxially grown on GaN using SrRuO3/TiO2 bufferlayer.