球差校正透射电镜技术探究SrTiO₃/SrTiO₃ 同质薄膜导电起源

A SrTiO₃ / SrTiO₃ homogeneous epitaxial film was grown along the SrTiO₃ substrate（001）by PLD method. The film was conductive before annealing，and became insulating states after annealing. A variety of advanced spherical aberration-corrected transmission microscopy techniques like annular high-angle darkfield image，annular brightfield image and atomic-resolution energy loss spectroscope（EELS）was used to explore the atomic occupancy，electronic structure and oxygen vacancies in the film. A TiO_x (1 < x < 2) reconstruction layer was found on the surface of the film. And the valence state of Ti in the reconstruction layer increases slightly after annealing. According to EELS analysis，oxygen vacancies existed in the whole film including the surface and interface before annealing，and disappeared after annealing. Therefore，for non-polar films SrTiO₃/SrTiO₃，oxygen vacancies near the film surface and interface maybe the origin of electrical conduction.