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arXiv 1712.00518cond-mat.mes-hall
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Al/Al2O3结的结构细节及其在电子隧道势垒形成中的作用

Structural details of Al/Al2O3 junctions and their role in formation of electron tunnel barriers

M. Koberidze, M. J. Puska, R. M. Nieminen

摘要:

我们提出了一个计算研究的Al/Al 2 O3界面的粘合剂和结构特性的金属-绝缘体-金属(MIM)隧道器件的积木,其中电子输运是通过隧道机制通过夹层绝缘屏障完成。本文的主要目标是了解,在原子尺度上,隧道势垒轮廓的形成中的几何细节的作用。为了提供可靠的结果,我们仔细评估用于检查Al/Al 2 O3界面的传统方法的准确性。这些是最广泛使用的交换相关泛函,LDA,PBE和PW 91,通用结合能关系(UBER)预测平衡界面距离和粘附能,以及理想的分离功作为衡量结稳定性。最后,我们进行了详细的分析,在每个结的原子和面间弛豫。我们的研究结果意味着,在Al膜的表面上的结构不规则性有显着的贡献,降低隧道势垒高度,而在Al膜的面间弛豫,远离直接接口不具有显着的影响隧穿性能。另一方面,多达5-7层的Al 2 O3可以参与隧道势垒的成形。这些层的面间弛豫取决于界面的几何形状,并且可能导致相对于体氧化物中的相应厚度的13%的净收缩。这是一个重要的量,因为隧穿概率指数地取决于势垒宽度。

英文摘要:

We present a computational study of the adhesive and structural properties of the Al/Al2O3 interfaces as building blocks of the Metal-Insulator-Metal (MIM) tunnel devices, where electron transport is accomplished via tunnelling mechanism through the sandwiched insulating barrier. The main goal of this paper is to understand, on the atomic scale, the role of the geometrical details in the formation of the tunnel barrier profiles. To provide reliable results, we carefully assess the accuracy of the traditional methods used to examine Al/Al2O3 interfaces. These are the most widely employed exchange-correlation functionals, LDA, PBE and PW91, the Universal Binding Energy Relation (UBER) for predicting equilibrium interfacial distances and adhesion energies, and the ideal work of separation as a measure of junction stability. Finally, we perform a detailed analysis of the atomic and interplanar relaxations in each junction. Our results imply that the structural irregularities on the surface of the Al film have a significant contribution to lowering the tunnel barrier height, while interplanar relaxations in the Al film, away from the immediate interface do not have a notable impact on the tunnelling properties. On the other hand, up to 5-7 layers of Al2O3 may be involved in shaping the tunnel barriers. Interplanar relaxations of these layers depend on the geometry of the interface and may result in the net contraction by 13% relative to the corresponding thickness in the bulk oxide. This is a significant amount as the tunnelling probability depends exponentially on the barrier width.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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