Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.
ACS Nano. 2012 Mar 27;6(3):2517-23. doi: 10.1021/nn204907t. Epub 2012 Feb 13.
With a thin insulator sandwiched between two electrodes, the negative differential resistance (NDR) behavior has been frequently reported for its potential device applications. Here we report the experimental observation of a symmetric NDR characteristic in a resistive switching device based on TiO(2). We propose a charge storage mechanism for the NDR effect, with oxygen molecular ions working as the active source, in a thin insulating layer. Current-voltage measurements demonstrated a highly reproducible state at about 0.65 eV, and the photoelectron spectroscopy measurements showed that it complies well with the Ti3d band gap state. Our first-principle calculations confirm that charge storage and release arise from trapping and detrapping of oxygen molecular ions at the defect sites. The results and mechanism demonstrated here in a thin layer could be extended to other systems approaching molecular dimensions for device applications.
在两个电极之间夹一层薄绝缘体，已经经常报道其具有负微分电阻（NDR）行为，因其具有潜在的器件应用。在这里，我们报告了基于 TiO2 的电阻开关器件中对称 NDR 特性的实验观察。我们提出了一种 NDR 效应的电荷存储机制，在薄绝缘层中，氧分子离子作为活性源。电流-电压测量显示在约 0.65 eV 处具有高度可重现的状态，光电电子能谱测量表明它与 Ti3d 带隙状态非常吻合。我们的第一性原理计算证实，电荷存储和释放源于在缺陷位置捕获和释放氧分子离子。这里在薄层中展示的结果和机制可以扩展到其他接近分子尺寸的系统，以用于器件应用。
