Dominant factor of contact resistance analyzed by conductive-AFM

Conductive AFM and in situ methods were used to determine contact resistance and resistivity of individual Sb2S3 nanowires. Nanowires were deposited on oxidized Si surface for in situ measurements and on Si surface with macroelectrodes for conductive AFM (C-AFM) measurements. Contact resistance was determined by measurement of I(V) characteristics at different distances from the nanowire contact with the macroelectrode and resistivity of nanowires was determined. Sb2S3 is a soft material with low adhesion force to the surface and therefore special precautions were taken during measurements.

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The Analysis of Mass Transport Phenomena in Micro Porous Layer for High Current Density Operation in PEMFC for Automobile Application

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2013-18126 ◽

2013 ◽

Cited By ~ 1

Author(s):

Toshikazu Kotaka ◽

Koichiro Aotani ◽

Yuichiro Tabuchi ◽

Partha Mukherjee

Keyword(s):

Contact Resistance ◽

Porous Layer ◽

Oxygen Transport ◽

Current Density ◽

High Current Density ◽

Transport Phenomena ◽

Dominant Factor ◽

High Current ◽

Micro Structure ◽

Carbon Particles

Cost reduction is the most important issue for commercialization of Fuel Cell Electric Vehicle (FCEV). High current density operation is one of the solutions for it. In order to realize high current density operation, it is necessary to reduce both of electron and oxygen transport resistance in the porous materials such as gas diffusion layer (GDL) and micro porous layer (MPL). However, the impacts of MPL microstructure on their properties are not fully understood yet compared with GDL because of the necessity of higher spatial resolution. In previous study, the transport analysis on the micro-structure which were visualized by Nano X-ray CT and FIB-SEM were conducted for it. However, it was not enough to understand both of the electron and oxygen transport phenomena and find the dominant factors, because there is no study which focused on the comparison of the numerical and experimental results on both of the electron and oxygen transport. In this study, the comprehensive analysis on both of electron and oxygen transport phenomena in GDL and MPL was conducted with experimental and numerical study based on the three-dimensional (3D) micro structure data. As a result, it was found that pore structure, such as a local porosity and/or tortuosity significantly affected the oxygen transport phenomena. On the other hands, especially in the case of electron transport phenomena in MPL, our results suggested that the dominant factor is not the solid structure such as local solid fraction and/or tortuosity but the contact resistance between carbon particles. This fact revealed that it is effective way to reduce the contact resistance between carbon particles and/or the number of contact points in unit length of a transport path in order to improve electrical transport of MPL.

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Influence of Thomson effect on amorphization in phase-change memory: Dimensional analysis based on Buckingham’s П theorem for Ge2Sb2Te5

Materials Research Express ◽

10.1088/2053-1591/ac3953 ◽

2021 ◽

Author(s):

Takuya Yamamoto ◽

Shogo Hatayama ◽

Yun-Heub Song ◽

Yuji Sutou

Keyword(s):

Contact Resistance ◽

Phase Change ◽

Temperature Increase ◽

Random Access ◽

Dominant Factor ◽

Thomson Effect ◽

Dimensionless Numbers ◽

Increasing Temperature ◽

Thomson Coefficient ◽

Change Material

Abstract To evaluate the Thomson effect on the temperature increase in Ge2Sb2Te5 (GST)-based phase-change random access memory (PCRAM), we created new dimensionless numbers based on Buckingham’s П theorem. The influence of the Thomson effect on the temperature increase depends on the dominant factor of electrical resistance in a PCRAM cell. When the effect is dominated by the volumetric resistance of the phase-change material (C=ρcΔx/σ≪O(1)), the dimensionless evaluation number is B=μTσ∆ϕk, where ρc is the contact resistance, Δx is the thickness of PCM, σ and k are the electrical and thermal conductivities, μT is the Thomson coefficient, and Δφ is the voltage. When the contact resistance cannot be ignored, the evaluation number is B/(1 + C). The characteristics of hexagonal-type crystalline GST in a PCRAM cell were numerically investigated using the defined dimensionless parameters. Although the contact resistance of GST exceeded the volumetric resistance across the temperature range, the ratio of contact resistance to the whole resistance reduced with increasing temperature. Moreover, increasing the temperature of GST enhanced the influence of the Thomson effect on the temperature distribution. At high temperatures, the Thomson effect suppressed the temperature increase by approximately 10–20%.

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Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126433 ◽

1987 ◽

Vol 45 ◽

pp. 326-327

Author(s):

A.K. Rai ◽

A.K. Petford-Long ◽

A. Ezis ◽

D.W. Langer

Keyword(s):

Contact Resistance ◽

Ohmic Contact ◽

Ohmic Contacts ◽

Microstructural Characterization ◽

Almost Everywhere ◽

Spacer Layer ◽

Good Contact ◽

The Relationship ◽

Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

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Thrombelastography during and after Elective Abdominal Surgery

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646708 ◽

1978 ◽

Vol 39 (02) ◽

pp. 488-495 ◽

Cited By ~ 13

Author(s):

J M Butler

Keyword(s):

Abdominal Surgery ◽

Factor Viii ◽

Whole Blood ◽

Dominant Factor ◽

Fibrinogen Concentration ◽

Factor Viii Activity ◽

Elective Abdominal Surgery

SummaryThrombelastography has been performed on recalcified whole blood from 50 patients before, during and after elective abdominal surgery. The characteristic changes of the thrombelastographic indices r, k and mA are described.During operation r and k shortened, but no change in mA was observed. This response was in part associated with an increase in factor VIII activity. Following operation, while r time was somewhat shortened, much more marked changes in k and mA were evident. Increasing fibrinogen concentration was the dominant factor in determining the post-operative changes in the thrombelastograph.

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Effect of No-load and Load Condition on Transformer Sound

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset184113 ◽

2018 ◽

pp. 11-15

Author(s):

Dr. Hitesh Paghadar

Keyword(s):

Experimental Study ◽

Power Transformer ◽

Load Condition ◽

Noise Pollution ◽

Sound Level ◽

Measurement Scale ◽

Dominant Factor ◽

Public Attention ◽

Level Measurement ◽

Human Ear

Increasing environment noise pollution is a matter of great concern and of late has been attracting public attention. Sound produces the minute oscillatory changes in air pressure and is audible to the human ear when in the frequency range of 20Hz to 20 kHz. The chief sources of audible sound are the magnetic circuit of transformer which produces sound due to magnetostriction phenomenon, vibration of windings, tank and other structural parts, and the noise produced by cooling equipments. This paper presents the validation for sound level measurement scale, why A-weighted scale is accepted for sound level measurement, experimental study carried out on 10MVA Power Transformer. Also presents the outcomes of comparison between No-Load sound & Load sound level measurement, experimental study carried out on different transformer like - 10MVA, 50MVA, 100MVA Power Transformer, to define the dominant factor of transformer sound generation.

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Degradation Phenomenon of Electrical Contacts by using a Micro-Sliding Mechanism -Modeling about Fluctuation of Contact Resistance-

IEICE Proceeding Series ◽

10.15248/proc.2.6 ◽

2014 ◽

Vol 2 ◽

pp. 6-9

Author(s):

Shin-ichi Wada ◽

Koichiro Sawa

Keyword(s):

Contact Resistance ◽

Electrical Contacts ◽

Sliding Mechanism ◽

Mechanism Modeling

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TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

MRS Proceedings ◽

10.1557/proc-764-c3.17 ◽

2003 ◽

Vol 764 ◽

Cited By ~ 3

Author(s):

D.N. Zakharov ◽

Z. Liliental-Weber ◽

A. Motayed ◽

S.N. Mohammad

Keyword(s):

Contact Resistance ◽

Ohmic Contacts ◽

High Resolution Electron Microscopy ◽

X Ray ◽

Electron Energy Loss Spectrometry ◽

Resolution Electron ◽

Order Of Magnitude ◽

Contact Surfaces ◽

Electron Energy Loss ◽

Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

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