Temperature dependence of carrier transport and resistance switching in Pt/SrTi1-xNbxO3 Schottky junctions
Temperature dependence of carrier transport and resistance switching in Pt/SrTi1-xNbxO3 Schottky junctions
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DOI：
10.1103/physrevb.83.125317
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发表时间：
2011-03-28
影响因子：
3.7
通讯作者：
Haneda, Hajime
中科院分区：
文献类型：
--
作者：
Li, Jianyong;Ohashi, Naoki;Haneda, Hajime
我们通过测量电流-电压 (I-V) 特性和电容-电压 (C-V) 特性的频率依赖性，研究了 Pt/SrTi1-xNbxO3 肖特基结在 80-400 K 温度范围内载流子传输和电阻切换的温度依赖性。 I-V 曲线表现出高度的磁滞，称为巨电阻（CER）效应，并且它们的温度依赖性表现出反常行为，即磁滞的幅度随着 T 的降低而增加。通过考虑 SrTi1-xNbxO3 相对介电常数的温度和电场依赖性以及肖特基势垒高度（SBH）的不均匀性来分析实验结果（肖特基势垒中两个并行电流路径共存的模型）。证实该模型很好地模拟了观察到的I-V和C-V曲线，从而表明CER效应源于通过不同SBH和肖特基结不同位置的场发射电流。基于这些结果，我们用这个模型定性地解释了CER效应的机制。为此，我们考虑了SBH小尺度不均匀性引起的夹断效应以及由于Pt/SrTi1-xNbxO3肖特基结耗尽层中的缺陷和无意杂质而存在深能级。
We investigated the temperature dependence of carrier transport and resistance switching of Pt/SrTi1-xNbxO3 Schottky junctions in the temperature range 80-400 K by measuring the current-voltage (I-V) characteristics and the frequency dependence of the capacitance-voltage (C-V) characteristics. The I-V curves displayed a high degree of hysteresis, known as the colossal electroresistance (CER) effect, and their temperature dependence showed an anomalous behavior, i.e., the magnitude of the hysteresis increased with decreasing T. The experimental results were analyzed by taking into account the temperature and electric-field dependence of the relative permittivity of SrTi1-xNbxO3 as well as the inhomogeneity of the Schottky barrier height (SBH) (a model in which two parallel current paths coexist in the Schottky barrier). It was confirmed that the observed I-V and C-V curves were well simulated by this model, thus indicating that the CER effects originated in the field emission current through different SBHs and at different locations of the Schottky junctions. Based on these results, we explain the mechanism of the CER effect qualitatively in terms of this model. For this purpose, we take into account the pinched-off effect caused by the small-scale inhomogeneity of SBH and the existence of deep levels as a result of defects and unintentional impurities in the depletion layer of the Pt/SrTi1-xNbxO3 Schottky junctions.