采用脉冲激光沉积法在（100）0．7wt％Nb：SrTi03（NSTO）衬底上制备了La0．8Sr0．2Mn03（LSMO）／NSTO（100）异质结，仔细研究了原位沉积氧压和真空退火对LSMO／NSTO异质结的结构及其整流伏安特性的调控．X-射线线性扫描和原子力显微镜测量显示，低氧压制备的LSMO／NST0（100）异质结具有良好的外延结构和平整的表面．电流-电压（I-V）盐线显示，沉积氧压为100mTorr的异质p～n结展现出极好的整流伏安特性；而氧压为240mTorr的异质p～n结平缓增加的电流可解释为异质P～n结在界面处晶格缺陷的增加．作为对比，沉积氧压调控的LSMO／SrTiO3（100）薄膜的输运性也被研究．电阻率结果显示，低氧压制备的LSMO薄膜，其电阻率的增加及金属-半导体转变温度L的降低归因于氧空位增加诱导的Mn4＋离子减少及MnO6八面体的畸变．
Heteroepitaxial junction composed of the La0. 8Sr0. 2 MnO3 (LSMO) and the (100) 0. 7wt Nb: SrTiOa (NSTO) has been fabricated by pulsed-laser deposition. The effect of the in-situ deposition oxygen pressures and the annealed in vacuum on the structure and the rectifying current-voltage behaviors in LSMO/NSTO(100) heterojunctions were carefully studied. X-ray linear scans and atomic force microscope (AFM) patterns indicate that the LSMO/NSTO(100) heterojunctions grown at lower oxygen pressures have a better epitaxial quality and the smooth surface. The result of current-voltage (I-V) curves shows that the p-n junction grown at oxygen pressure of 100 mTorr exhibits an excellent rectifying behavior, but the p-n junction grown at a pressure of 240 mTorr displays a flat the I-V curves, which is ascribed to the increase of the lattice defects in pun junction interface. As a contrast,the transport properties of epitaxial LSMO/SrTiO3 (100) films were also studied by the modulating deposition oxygen pressures. The resistivity measurements shown that the increase of overall resistivity and the low of metal-insulator transition temperatures Tp in the LSMO films grown at lower oxygen pressures can be aseribed to the oxygen vaeancy inducing the decrease of Mn4+ ions as well as the distortion of MnO6 octahedron
参考文献
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