A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts

Abstract

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.

Multiscale modeling and numerical analyses of the electric conductivity of CNT/polymer nanocomposites taking into account the tunneling effect

“…In this case, most of the tunneling current is formed from tip to tip of CNTs in the x direction and the error that comes from the assumption of tunneling current is reduced. If the volume fraction of aligned CNTs is high, the electric contacts by the electric tunneling in parallel CNTs can not be neglected and should be modified as presented by Banerjee et al 71 Another conclusion is that aligning the CNTs leads to a larger percolation threshold and a sharper increase in conductivity after the percolation threshold, as compared to randomly oriented CNTs. Thus, the randomly distributed CNTs present to be more conductive than aligned CNTs at low CNT volume fraction.…”

Passive Intermodulation at Contacts of Rough Conductors

“…The accuracy of the Simmons model (4) of MIM junctions was recently examined for thin insulator films in [26][27][28][29]. The simulated characteristics of J(V g ) in the MIM junction are shown in Figure 3 for an insulating film with a thickness of 1 nm.…”

“…PIM phenomenology has been studied for more than 40 years but still remains a nagging problem. The basic physical mechanisms of nonlinearities and PIM generation were explored in metal contacts [22][23][24][25][26][27][28][29], printed RF transmission lines [30][31][32][33][34][35][36], cable assemblies [17,18,31,[37][38][39][40] and antennas [21,[41][42][43][44][45]. The main sources of passive nonlinearities include Metal-Insulator-Metal (MIM) junctions [22][23][24][26][27][28][29], electro-thermal processes [37,40,46,47], surface roughness [32,48,49] and contact mechanical deformations [49][50][51][52][53].…”

“…The basic physical mechanisms of nonlinearities and PIM generation were explored in metal contacts [22][23][24][25][26][27][28][29], printed RF transmission lines [30][31][32][33][34][35][36], cable assemblies [17,18,31,[37][38][39][40] and antennas [21,[41][42][43][44][45]. The main sources of passive nonlinearities include Metal-Insulator-Metal (MIM) junctions [22][23][24][26][27][28][29], electro-thermal processes [37,40,46,47], surface roughness [32,48,49] and contact mechanical deformations [49][50][51][52][53]. The advent of micro-electro-mechanical systems (MEMS) has sparked extensive investigations of the electrical contacts with rough surfaces and their RF performance.…”

Temperature Comparison of Looped and Vertical Carbon Nanotube Fibers during Field Emission

“…It is also important to note that near the top of the looped fiber, only one side of the fiber faces the anode to emit current (Figure 2b). Because of the high inter-tube resistance [40][41][42], the resistance of the small fraction of conducting fibrils in a CNT fiber during field emission will be significantly higher than that of the overall macroscopic fiber.…”