Beijing National Laboratory for Condensed, Matter Physics Institute of Physics, Chinese Academy of Science, Beijing 100190, China.
Small. 2012 Apr 23;8(8):1279-84. doi: 10.1002/smll.201101796. Epub 2012 Feb 20.
LaMnO(3) (LMO) films are deposited on SrTiO(3):Nb (0.8 wt%) substrates under various oxygen pressures to obtain different concentrations of oxygen vacancies in the films. The results of X-ray diffraction verify that with a decrease of the oxygen pressure, the c-axis lattice constant of the LMO films becomes larger, owing to an increase of the oxygen vacancies. Aberration-corrected annular-bright-field scanning transmission electron microscopy with atomic resolution and sensitivity for light elements is used, which clearly shows that the number of oxygen vacancies increases with the decrease of oxygen pressure during fabrication. Correspondingly, the resistive switching property becomes more pronounced with more oxygen vacancies in the LMO films. Furthermore, a numerical model based on the modification of the interface property induced by the migration of oxygen vacancies in these structures is proposed to elucidate the underlying physical origins. The calculated results are in good agreement with the experimental data, which reveal from a theoretical point of view that the migration of oxygen vacancies and the variation of the Schottky barrier at the interface with applied bias dominate the resistive switching characteristic. It is promising that the resistive switching property in perovskite oxides can be manipulated by controlling the oxygen vacancies during fabrication or later annealing in an oxygen atmosphere.
LaMnO(3)（LMO）薄膜在不同氧压下沉积在 SrTiO(3):Nb（0.8wt%）衬底上，以获得薄膜中不同浓度的氧空位。X 射线衍射的结果证实，随着氧压的降低，LMO 薄膜的 c 轴晶格常数变大，这是由于氧空位的增加。使用具有原子分辨率和轻元素灵敏度的校正像差环形明场扫描透射电子显微镜，清楚地表明在制备过程中，随着氧压的降低，氧空位的数量增加。相应地，LMO 薄膜中氧空位越多，电阻开关性能越明显。此外，还提出了一个基于这些结构中氧空位迁移引起的界面性质改性的数值模型，以阐明其物理起源。计算结果与实验数据吻合较好，从理论上揭示了氧空位的迁移和施加偏压时界面肖特基势垒的变化主导了电阻开关特性。有望通过控制制备过程中的氧空位或随后在氧气气氛中的退火来操纵钙钛矿氧化物中的电阻开关性能。
