scholarly journals Characterization of the Resistance and Force of a Carbon Nanotube/Metal Side Contact by Nanomanipulation

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Ning Yu ◽  
Masahiro Nakajima ◽  
Qing Shi ◽  
Zhan Yang ◽  
Huaping Wang ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Contact Force ◽  
Contact Area ◽  
Field Effect Transistors ◽  
Influence Factors ◽  
Contact Length ◽  
Before And After ◽  
Negative Exponential ◽  
Good Agreement

A high contact resistance restricts the application of carbon nanotubes (CNTs) in fabrication of field-effect transistors (FETs). Thus, it is important to decrease the contact resistance and investigate the critical influence factors such as the contact length and contact force. This study uses nanomanipulation to characterize both the resistance and the force at a CNT/Au side-contact interface inside a scanning electron microscopy (SEM). Two-terminal CNT manipulation methods, and models for calculating the resistance and force at contact area, are proposed to guide the measurement experiments of a total resistance and a cantilever’s elastic deformation. The experimental results suggest that the contact resistance of CNT/Au interface is large (189.5 kΩ) when the van der Waals force (282.1 nN) dominates the contact force at the interface. Electron-beam-induced deposition (EBID) is then carried out to decrease the contact resistance. After depositing seven EBID points, the resistance is decreased to 7.5 kΩ, and the force increases to 1339.8 nN at least. The resistance and force at the contact area where CNT was fixed exhibit a negative exponential correlation before and after EBID. The good agreement of this correlation with previous reports validates the proposed robotic system and methods for characterizing the contact resistance and force.

scholarly journals Use of Mini-CT Specimens for Fracture Toughness Characterization of Low Upper-Shelf Linde 80 Weld Before and After Irradiation

2018 ◽  
Author(s):  
Mikhail A. Sokolov
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Collaborative Program ◽  
Before And After ◽  
Minimum Number ◽  
Real Practice ◽  
Reactor Pressure ◽  
Good Agreement

Mini-CT specimens are becoming a highly popular geometry for use in reactor pressure vessel (RPV) community for direct measurement of fracture toughness in the transition region using the Master Curve methodology. In the present study, Mini-CT specimens were machined from previously tested Charpy specimens of the Midland low upper-shelf Linde 80 weld in both, unirradiated and irradiated conditions. The irradiated specimens have been characterized as part of a joint ORNL-EPRI-CRIEPI collaborative program. The Linde 80 weld was selected because it has been extensively characterized in the irradiated condition by conventional specimens, and because of the need to validate application of Mini-CT specimens for low upper-shelf materials — a more likely case for some irradiated materials of older generation RPVs. It is shown that the fracture toughness reference temperatures, To, derived from these Mini-CT specimens are in good agreement with To values previously recorded for this material in the unirradiated and irradiated conditions. However, this study indicates that in real practice it is highly advisable to use a much larger number of specimens than the minimum number prescribed in ASTM E1921.

scholarly journals Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect

2020 ◽  
Vol 12 (10) ◽  
pp. 1669
Author(s):  
Krista Alikas ◽  
Viktor Vabson ◽  
Ilmar Ansko ◽  
Gavin H. Tilstone ◽  
Giorgio Dall’Olmo ◽  
...  
Keyword(s):  
State Of The Art ◽  
Ocean Color ◽  
Percentage Difference ◽  
Wide Range ◽  
Before And After ◽  
Reference Measurements ◽  
Satellite Ocean Color ◽  
Good Agreement

The Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) project has carried out a range of activities to evaluate and improve the state-of-the-art in ocean color radiometry. This paper described the results from a ship-based intercomparison conducted on the Atlantic Meridional Transect 27 from 23rd September to 5th November 2017. Two different radiometric systems, TriOS-Radiation Measurement Sensor with Enhanced Spectral resolution (RAMSES) and Seabird-Hyperspectral Surface Acquisition System (HyperSAS), were compared and operated side-by-side over a wide range of Atlantic provinces and environmental conditions. Both systems were calibrated for traceability to SI (Système international) units at the same optical laboratory under uniform conditions before and after the field campaign. The in situ results and their accompanying uncertainties were evaluated using the same data handling protocols. The field data revealed variability in the responsivity between TRiOS and Seabird sensors, which is dependent on the ambient environmental and illumination conditions. The straylight effects for individual sensors were mostly within ±3%. A near infra-red (NIR) similarity correction changed the water-leaving reflectance (ρw) and water-leaving radiance (Lw) spectra significantly, bringing also a convergence in outliers. For improving the estimates of in situ uncertainty, it is recommended that additional characterization of radiometers and environmental ancillary measurements are undertaken. In general, the comparison of radiometric systems showed agreement within the evaluated uncertainty limits. Consistency of in situ results with the available Sentinel-3A Ocean and Land Color Instrument (OLCI) data in the range from (400…560) nm was also satisfactory (−8% < Mean Percentage Difference (MPD) < 15%) and showed good agreement in terms of the shape of the spectra and absolute values.

Electrical Characterization of Ion Imiplanted, Thermally Annealed TiN Films Acting as Diffusion Barriers on Shallow Junction Silicon Devices

1985 ◽  
Vol 45 ◽  
Author(s):  
A. Armigliato ◽  
M. Finetti ◽  
E. Gabilli ◽  
S. Guerri ◽  
P. Ostoja ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Contact Area ◽  
Electrical Characterization ◽  
Diffusion Barriers ◽  
Contact Structures ◽  
Thermal Treatments ◽  
Tin Films ◽  
Shallow Junction ◽  
Silicon Devices

ABSTRACTTiN films prepared by implantation onto evaporated Ti layers are tested as diffusion barriers in contact with a thick Al overlayer. Both the TiN/Al and TiSi2/TiN/Al contact structures are evaluated, after thermal treatments up to 600 C, on shallow junction diodes and four terminal resistor test patterns for contact resistance measurements. It is shown that, upon annealing at 600 C, the TiSi2/TiN/Al contact system still exhibits excellent electrical performances. The degradation is found to depend on TiSi2 thickness and contact area.

scholarly journals Comparisons between ground-based FTIR and MIPAS N<sub>2</sub>O and HNO<sub>3</sub> profiles before and after assimilation in BASCOE

2006 ◽  
Vol 6 (5) ◽  
pp. 8335-8382
Author(s):  
C. Vigouroux ◽  
M. De Mazière ◽  
Q. Errera ◽  
E. Mahieu ◽  
P. Duchatelet ◽  
...  
Keyword(s):  
Standard Deviation ◽  
High Latitude ◽  
Atmospheric Composition ◽  
Upper Troposphere ◽  
Before And After ◽  
Standard Deviations ◽  
Data Assimilation System ◽  
Good Agreement ◽  
Middle Stratosphere

Abstract. Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared (FTIR) measurements of many species are performed at several locations. Inversion schemes provide vertical profile information and characterization of the retrieved products which are therefore relevant for contributing to the validation of MIPAS profiles in the stratosphere and upper troposphere. We have focused on the species HNO3 and N2O at 5 NDACC-sites distributed in both hemispheres, i.e., Jungfraujoch (46.5° N) and Kiruna (68° N) for the northern hemisphere, and Wollongong (34° S), Lauder (45° S) and Arrival Heights (78° S) for the southern hemisphere. These ground-based data have been compared with MIPAS offline profiles (v4.61) for the year 2003, collocated within 1000 km around the stations, in the lower to middle stratosphere. To get around the spatial collocation problem, comparisons have also been made between the same ground-based FTIR data and the corresponding profiles resulting from the stratospheric 4D-VAR data assimilation system BASCOE. This paper discusses the results of the comparisons and the usefullness of using BASCOE profiles as proxies for MIPAS data. It shows good agreement between MIPAS and FTIR N2O partial columns: the biases are below 5% for all the stations and the standard deviations are below 7% for the three mid-latitude stations, and below 10% for the high latitude ones. The comparisons with BASCOE partial columns give standard deviations below 4% for the mid-latitude stations to less than 8% for the high-latitude ones. After making some corrections to take into account the known bias due to the use of different spectroscopic parameters, the comparisons of HNO3 partial columns show biases below 3% and standard deviations below 15% for all the stations except Arrival Heights (bias of 6%, standard deviation of 21%). The results for this species, which has a larger spatial variability, highlight the necessity of defining appropriate collocation criteria and of accounting for the spread of the observed airmasses. BASCOE appears to have more deficiencies in producing proxies of MIPAS HNO3 profiles compared to N2O, but the obtained standard deviation of less than 10% between BASCOE and FTIR is reasonable. Similar results on profiles comparisons are also shown in the paper, in addition to partial column ones.

scholarly journals Plackett–Burman Combined with Box–Behnken to Optimize the Medium of Fermented Tremella Polysaccharide and Compare the Characteristics before and after Optimization

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xia Ma ◽  
Meng Yang ◽  
Yan He ◽  
Chenglinang Li ◽  
Chuntao Zhai
Keyword(s):  
Monosaccharide Composition ◽  
Fermentation Medium ◽  
Surface Method ◽  
Before And After ◽  
Acid Polysaccharide ◽  
Burman Design ◽  
Potato Extract ◽  
Plackett Burman Design ◽  
Good Agreement

The purpose of this study was to improve the yield of fermented Tremella polysaccharide (FTP) by optimizing the medium and to explore the effect of optimization on the structure. In this paper, the Plackett–Burman design and response surface method were used to optimize the fermentation medium of Tremella spore GT2# for FTP production. The results of the Plackett–Burman design showed that potato extract, glucose, and peptone were the main factors. The Box–Behnken experiment and regression analysis determined that the optimal concentrations of potato extract, glucose, and peptone were 22.01%, 29.38 g/L, and 2.61 g/L, respectively. After optimization, the fermentation period shortened from 5 days to 3 days, and the yield of FTP increased from 10.75 g/L to 12.50 g/L, which was in good agreement with the predicted value (12.36 g/L). Characterization of FTP obtained before and after optimization was carried out, and the results showed that medium optimization had significant effects on the primary structure of FTP, including molecular weight, monosaccharide composition, and proportion. After optimization, the content of acid polysaccharide increased, and the glycoside bonds changed from a-configuration to ß-configuration.

Solvent Soaking and Drying of Carbon Nanotube Forests for Enhanced Contact Area and Thermal Interface Conductance

2013 ◽  
Author(s):  
John H. Taphouse ◽  
Baratunde A. Cola
Keyword(s):  
Contact Resistance ◽  
Contact Area ◽  
Thermal Contact ◽  
Van Der Waals ◽  
Phonon Transport ◽  
Van Der Waals Interactions ◽  
Thermal Interface ◽  
Before And After ◽  
Carbon Nanotube Forests ◽  
Opposing Surface

Forests comprised of nominally vertically aligned carbon nanotubes (CNTs), having outstanding thermal and mechanical properties, are excellent candidates for thermal interface materials (TIMs). However, the thermal performance of CNT forest TIMs has been limited by the presence of high thermal contact resistances at the CNT tip interface. The high thermal contact resistance at the CNT tip interface stems from two sources: (1) the relatively weak van der Waals type bonding, which impedes phonon transport, and (2) low contact area. In this work we will show that common solvents, such as water, can be applied to the CNT forest to increase the contact area and reduce the contact resistance by an average of 75%. Specifically, there are two likely mechanisms that can increase the contact area when a CNT forest is wet with a fluid and compressed in an interface. The first is relaxing the van der Waals interactions between contacting CNTs within the forest, consequently decreasing the stiffness of the forest and allowing it to better conform to the opposing surface. The second is the pulling of CNT tips through capillary interactions into contact with the opposing surface as the solvent evaporates. By measuring the thermal resistance of CNT TIMs before and after soaking in variety of solvents the capacity of each mechanism for reducing the contact resistance is explored.

scholarly journals Comparisons between ground-based FTIR and MIPAS N<sub>2</sub>O and HNO<sub>3</sub> profiles before and after assimilation in BASCOE

2007 ◽  
Vol 7 (2) ◽  
pp. 377-396 ◽  
Author(s):  
C. Vigouroux ◽  
M. De Mazière ◽  
Q. Errera ◽  
S. Chabrillat ◽  
E. Mahieu ◽  
...  
Keyword(s):  
Standard Deviation ◽  
High Latitude ◽  
Atmospheric Composition ◽  
Upper Troposphere ◽  
Before And After ◽  
Standard Deviations ◽  
Data Assimilation System ◽  
Good Agreement ◽  
Middle Stratosphere

Abstract. Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared (FTIR) measurements of many species are performed at several locations. Inversion schemes provide vertical profile information and characterization of the retrieved products which are therefore relevant for contributing to the validation of MIPAS profiles in the stratosphere and upper troposphere. We have focused on the species HNO3 and N2O at 5 NDACC-sites distributed in both hemispheres, i.e., Jungfraujoch (46.5° N) and Kiruna (68° N) for the northern hemisphere, and Wollongong (34° S), Lauder (45° S) and Arrival Heights (78° S) for the southern hemisphere. These ground-based data have been compared with MIPAS offline profiles (v4.61) for the year 2003, collocated within 1000 km around the stations, in the lower to middle stratosphere. To get around the spatial collocation problem, comparisons have also been made between the same ground-based FTIR data and the corresponding profiles resulting from the stratospheric 4D-VAR data assimilation system BASCOE constrained by MIPAS data. This paper discusses the results of the comparisons and the usefullness of using BASCOE profiles as proxies for MIPAS data. It shows good agreement between MIPAS and FTIR N2O partial columns: the biases are below 5% for all the stations and the standard deviations are below 7% for the three mid-latitude stations, and below 10% for the high latitude ones. The comparisons with BASCOE partial columns give standard deviations below 4% for the mid-latitude stations to less than 8% for the high latitude ones. After making some corrections to take into account the known bias due to the use of different spectroscopic parameters, the comparisons of HNO3 partial columns show biases below 3% and standard deviations below 15% for all the stations except Arrival Heights (bias of 5%, standard deviation of 21%). The results for this species, which has a larger spatial variability, highlight the necessity of defining appropriate collocation criteria and of accounting for the spread of the observed airmasses. BASCOE appears to have more deficiencies in producing proxies of MIPAS HNO3 profiles compared to N2O, but the obtained standard deviation of less than 10% between BASCOE and FTIR is reasonable. Similar results on profiles comparisons are also shown in the paper, in addition to partial column ones.

An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

1973 ◽  
Vol 31 ◽  
pp. 32-33 ◽  
Author(s):  
T. C. Tisone ◽  
S. Lau
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Thermally Grown Oxide ◽  
Ion Milling ◽  
Compound Formation ◽  
Technology Application ◽  
Transmission Electron ◽  
Before And After ◽  
Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

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

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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