Epitaxial Growth and Ferroelectricity of BaTiO_3 on SrRuO_3/TiO_2 Buffered GaN

摘要

Epitaxial growth of (111)-oriented BaTiO_3 thin films on GaN/Al_2O_3 (0001) substrates has been realized by intervening epitaxial (111) SrRuO_3/(100)TiO_2 buffer layers. Rutile TiO_2 was deposited by Laser molecular beam epitaxial firstly and the deposition process of TiO_2 layer was in-situ monitored by reflective high energy electron diffractions. After that SrRuO_3 conductive films and BaTiO_3ferroelectric films were fabricated via pulsed laser deposition. The perovskite BaTiO_3 films were epitaxially grown on wurtzite GaN as revealed by X-ray diffraction. Electrical measurements demonstrate that the BaTiO_3 films possess a saturation ferroelectric hysteresis loop, butterfly-shape C-V curve and low leakage current density. These results show that BaTiO_3 films with favorable electrical performance could be epitaxially grown on GaN using SrRuO_3/TiO_2 bufferlayer.