Banerjee Sneha, Luginsland John, Zhang Peng
Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan, 48824-1226, USA.
Confluent Sciences, LLC, Albuquerque, New Mexico, 87111, USA.
Sci Rep. 2019 Oct 9;9(1):14484. doi: 10.1038/s41598-019-50934-2.
Contact resistance and current crowding are important to nanoscale electrical contacts. In this paper, we present a self-consistent model to characterize partially overlapped parallel contacts with varying specific contact resistivity along the contact length. For parallel tunneling contacts formed between contacting members separated by a thin insulating gap, we examine the local voltage-dependent variation of potential barrier height and tunneling current along the contact length, by solving the lumped circuit transmission line model (TLM) equations coupled with the tunneling current self consistently. The current and voltage distribution along the parallel tunneling contacts and their overall contact resistance are analyzed in detail, for various input voltage, electrical contact dimension, and material properties (i.e. work function, sheet resistance of the contact members, and permittivity of the insulating layer). It is found the existing one-dimensional (1D) tunneling junction models become less reliable when the tunneling layer thickness becomes smaller or the applied voltage becomes larger. In these regimes, the proposed self-consistent model may provide a more accurate evaluation of the parallel tunneling contacts. For the special case of constant ohmic specific contact resistivity along the contact length, our theory has been spot-checked with finite element method (FEM) based numerical simulations. This work provides insights on the design, and potential engineering, of nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry.
接触电阻和电流拥挤现象对于纳米级电接触非常重要。在本文中，我们提出了一种自洽模型，用于表征沿接触长度具有不同比接触电阻率的部分重叠平行接触。对于由薄绝缘间隙隔开的接触部件之间形成的平行隧穿接触，我们通过自洽求解集总电路传输线模型（TLM）方程与隧穿电流，研究了沿接触长度的势垒高度和隧穿电流的局部电压依赖性变化。针对各种输入电压、电接触尺寸和材料特性（即功函数、接触部件的薄层电阻以及绝缘层的介电常数），详细分析了沿平行隧穿接触的电流和电压分布及其总接触电阻。研究发现，当隧穿层厚度变小或施加电压变大时，现有的一维（1D）隧穿结模型变得不太可靠。在这些情况下，所提出的自洽模型可以对平行隧穿接触提供更准确的评估。对于沿接触长度具有恒定欧姆比接触电阻率的特殊情况，我们的理论已通过基于有限元方法（FEM）的数值模拟进行了验证。这项工作为通过设计空间变化的接触层特性和几何形状来控制电流分布和接触电阻的纳米级电接触的设计及潜在工程应用提供了见解。
