Metal-insulator-metal structures based on ultrathin high-$k$ dielectric films are underpinning a rapidly increasing number of devices and applications. Here, we report detailed electrical characterizations of asymmetric metal-insulator-metal devices featuring atomic layer deposited 2-nm-thick ${\mathrm{Al}}_2{\mathrm{O}}_3$ films. We find a high consistency in the current density as a function of applied electric field between devices with very different surface areas and significant asymmetries in the $\mathit{IV}$ characteristics. We show by TEM that the thickness of the dielectric film and the quality of the metal-insulator interfaces are highly uniform and of high quality, respectively. In addition, we develop a model which accounts for the field enhancement due to the small sharp features on the electrode surface and show that this can very accurately describe the observed asymmetry in the current-voltage characteristic, which cannot be explained by the difference in work function alone.

中文翻译：

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超薄原子层沉积生长的Au-Al2O3-Cr金属-绝缘体-金属结构中的场增强直接隧穿

基于超薄高合金的金属-绝缘体-金属结构$ķ$介电膜为迅速​​增长的设备和应用提供了基础。在这里，我们报告了以2纳米厚的原子层沉积为特征的不对称金属-绝缘体-金属器件的详细电学特性${铝}_{\mathrm{2个}}{\mathrm{Ø}}_3$电影。我们发现电流密度的高一致性是器件之间施加的电场的函数，这些器件的表面积非常不同，并且存在很大的不对称性。$\mathit{IV}$特征。我们通过TEM证明介电膜的厚度和金属-绝缘体界面的质量分别是高度均匀和高质量的。此外，我们开发了一个模型，该模型考虑了由于电极表面上小的尖锐特征而引起的电场增强，并表明这可以非常准确地描述所观察到的电流-电压特性中的不对称性，这不能用功的差异来解释。独自发挥作用。