Degradation Phenomenon of Electrical Contacts by Oscillating Mechanisms - Modeling about Fluctuation of Contact Resistance -

2014 ◽  
Vol 1 ◽  
pp. 872-875
Author(s):  
Shin-ichi Wada ◽  
Koichiro Sawa
Keyword(s):  
Contact Resistance ◽  
Electrical Contacts

End-bonded contacts for carbon nanotube transistors with low, size-independent resistance

Science ◽  
2015 ◽  
Vol 350 (6256) ◽  
pp. 68-72 ◽  
Author(s):  
Qing Cao ◽  
Shu-Jen Han ◽  
Jerry Tersoff ◽  
Aaron D. Franklin ◽  
Yu Zhu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Contact Resistance ◽  
High Performance ◽  
Contact Length ◽  
Electrical Contacts ◽  
Single Walled Carbon Nanotube ◽  
Device Resistance ◽  
Silicon Transistors ◽  
Nanotube Transistors ◽  
P Type

Moving beyond the limits of silicon transistors requires both a high-performance channel and high-quality electrical contacts. Carbon nanotubes provide high-performance channels below 10 nanometers, but as with silicon, the increase in contact resistance with decreasing size becomes a major performance roadblock. We report a single-walled carbon nanotube (SWNT) transistor technology with an end-bonded contact scheme that leads to size-independent contact resistance to overcome the scaling limits of conventional side-bonded or planar contact schemes. A high-performance SWNT transistor was fabricated with a sub–10-nanometer contact length, showing a device resistance below 36 kilohms and on-current above 15 microampere per tube. The p-type end-bonded contact, formed through the reaction of molybdenum with the SWNT to form carbide, also exhibited no Schottky barrier. This strategy promises high-performance SWNT transistors, enabling future ultimately scaled device technologies.

Influence of Surface Roughness on Friction and Contact Resistance in Sliding Electrical Contacts

2007 ◽  
Author(s):  
Dinesh G. Bansal ◽  
Jeffrey L. Streator
Keyword(s):  
Surface Roughness ◽  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Electrical Contact ◽  
Electrical Current ◽  
Electrical Contacts ◽  
Sliding Electrical Contacts ◽  
The Coefficient Of Friction ◽  
Current Densities

An experiment is conducted to investigate the role of surface roughness on the coefficient of friction and contact resistance of sliding electrical contacts. A hemispherical pin is sliding along both smooth and rough 2-meter rail surface. Tests are performed at both low and moderate sliding speed and for a range of electrical current densities, ranging from 0 to about 12 GA/m2. It was found that surface roughness had a significant influence on the coefficient of friction, with the smoother surfaces exhibiting higher coefficients of friction. Contact resistance, on the other hand, did not show as strong an effect of surface roughness, except for a few parameter combinations. At the higher current densities studied (>10 GA/m2), it was found that the contact resistance values tended to be on the order of 1 mΩ, independent of load, speed and roughness. This convergence may be due to presence of liquid metal film at the interface, which established ideal electrical contact.

Requirements of Electrical Contacts to Photovoltaic Solar Cells

1990 ◽  
Vol 184 ◽  
Author(s):  
T. A. Gessert ◽  
T. J. Coutts
Keyword(s):  
Solar Cells ◽  
Contact Resistance ◽  
Large Scale ◽  
Electrical Contacts ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
Large Scale Integration ◽  
Adverse Environmental Conditions ◽  
Scale Integration ◽  
Photovoltaic Solar Cells

ABSTRACTThe importance of contacts to photovoltaic solar cells is often underrated mainly because the required values of specific contact resistance and metal resistivity are often thought to be relatively modest compared with those associated with very large scale integration (VLSI) applications. However, due to the adverse environmental conditions experienced by solar cells, and since many of the more efficient cells are economically advantageous only when operated under solar concentration, the requirements for solar cell contacts are sometimes more severe. For example, at one-sun operation, the upper limit in specific contact resistance is usually taken to be 10−2 Ω-cm2. However, at several hundred suns, this value should be reduced to less than 10−4 Ω-cm2. Additionally, since grid line fabrication often relies on economical plating processes, porosity and contamination issues can be expected to cause reliability and stability problems once the device is fabricated. It is shown that, in practice, these metal resistivity issues can be much more important than issues relating to specific contact resistance and that the problem is similar to that of providing stable, low resistance interconnects in VLSI. This paper is concerned with the design and fabrication of collector grids on the front of the solar cells and, although the discussion is fairly general, it will center on the particular material indium phosphide. This III-V material is currently of great importance for space application because of its resistance to the damaging radiation experienced in space.

Simulation of Thermal Effects in Stationary and Sliding Electrical Contacts

2008 ◽  
Author(s):  
Bobby G. Watkins ◽  
Jeffrey Streator
Keyword(s):  
Contact Resistance ◽  
Electrical Contact ◽  
Transient Heat Conduction ◽  
Surface Damage ◽  
Electrical Contacts ◽  
Maximum Temperature ◽  
High Resistivity ◽  
Electrical Contact Resistance ◽  
Material Loss ◽  
Sliding Electrical Contacts

Sliding electrical contacts are subject to surface damage and wear, which can be enhanced by the heating at the interface arising from electrical contact resistance. For example, in electromagnetic launcher (EML) technology, thermally assisted wear processes can result in unacceptable levels of material loss at the armature-rail interface. The control of the interface tribology in sliding electrical contacts requires an understanding of the Joule heating in the vicinity of the interface. In the current study, a multiphysics numerical simulation is conducted of transient heat conduction in both a stationary and a sliding electrical contact. The interface under investigation consists of a flat-ended aluminum cylindrical pin sliding against an aluminum rail. Electrical contact resistance is modeled by introducing a thin layer of high resistivity between the pin and the rail. Results show that shortly after sliding has commenced, (1) the maximum temperature rise occurs in the bulk of the pin rather than at the interface, (2) the bulk of the Joule heat goes into the rail, and (3) that sliding can have a significant effect on the temperature field, even when the speed is quite low.

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

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sneha Banerjee ◽  
John Luginsland ◽  
Peng Zhang
Keyword(s):  
Contact Resistance ◽  
Transmission Line ◽  
Tunneling Current ◽  
Contact Length ◽  
Electrical Contacts ◽  
Transmission Line Model ◽  
Consistent Model ◽  
Self Consistent ◽  
Specific Contact ◽  
Specific Contact Resistivity

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.

Reducing Contact Resistance in Two-Dimensional-Material-Based Electrical Contacts by Roughness Engineering

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Sneha Banerjee ◽  
Liemao Cao ◽  
Yee Sin Ang ◽  
L.K. Ang ◽  
Peng Zhang
Keyword(s):  
Contact Resistance ◽  
Electrical Contacts ◽  
Two Dimensional

scholarly journals In-Situ Fretting Wear Analysis of Electrical Connectors for Real System Applications

2019 ◽  
Vol 3 (2) ◽  
pp. 47 ◽  
Author(s):  
Arpith Siddaiah ◽  
Ashish K. Kasar ◽  
Vishal Khosla ◽  
Pradeep L. Menezes
Keyword(s):  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Electrical Contact ◽  
Electrical Contacts ◽  
Fretting Wear ◽  
Electrical Contact Resistance ◽  
Contact Loads ◽  
High Degree ◽  
Electrical Connectors

The tribological behavior of electrical contacts, especially separable type electrical connectors at low contact loads, are considered. The reliability of these connectors has been a major concern due to the fretting phenomenon that can lead to an unacceptable increase in contact resistance. This study analyzes various aspects of the fretting mechanism from a tribological perspective where friction and wear are the primary cause of degradation in electrical components. With the use of precise tribological equipment (high data acquisition rate of 5000 Hz), the electrical contact resistance and coefficient of friction at the contact interface are measured. The measurements were made in-situ for a simulated fretting environment under various constant loading conditions. It was observed that low contact loads (1 N) and low fretting frequency (1 Hz) leads to a high degree of fluctuation in the coefficient of friction. However, for the same conditions, the lowest wear rate and electrical contact resistance were observed. The reason behind this could be due to the lack of continuous electrical contact and a high degree of fretting frequency under low contact loads, ultimately leading to extended periods of an open circuit. Experimental analysis indicates the existence of an optimum loading condition at which the fretting wear effect is at its minimum. Detailed analysis of post fretting surface roughness, coating wear, and wear debris is conducted, as well as transfer film formations to explain the mechanism of fretting observed.

Low-Resistance Electrical Contacts to p-Type GaN by Using InxGa1-xN Cap Layers

2001 ◽  
Vol 693 ◽  
Author(s):  
Th. Gessmann ◽  
Y.-L. Li ◽  
J. W. Graff ◽  
E. F. Schubert ◽  
J. K. Sheu
Keyword(s):  
Contact Resistance ◽  
Electric Fields ◽  
Ohmic Contacts ◽  
Electrical Contacts ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Transmission Line Method ◽  
Specific Contact ◽  
P Type ◽  
20 Nm

AbstractA novel type of low-resistance ohmic contacts is demonstrated utilizing polarization-induced electric fields in thin p-type InGaN layers on p-type GaN. An increase of the hole tunneling probability through the barrier and a concomitant significant decrease of the specific contact resistance can be attributed to a reduction of the tunneling barrier width in the InGaN capping layers due to the polarization-induced electric fields. The specific contact resistance of Ni (10 nm) / Au (30 nm) contacts deposited on the InGaN capping layers was determined by the transmission line method. Specific contact resistances of 1.2 × 10-2 Ω cm2 and 6 × 10-3 & cm2 were obtained for capping layer thicknesses of 20 nm and 2 nm, respectively.

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