Electron Emission from Microwave-Plasma Chemically Vapor Deposited Carbon Nanotubes

2000 ◽  
Vol 621 ◽  
Author(s):  
Yonhua Tzeng ◽  
Chao Liu ◽  
Calvin Cutshaw ◽  
Zheng Chen
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Electron Emission ◽  
Microwave Plasma ◽  
High Vacuum ◽  
Field Enhancement ◽  
Current Voltage ◽  
Microwave Plasma Cvd ◽  
Field Emission Of Electrons

ABSTRACTA microwave plasma CVD reactor was used for the deposition of carbon nanotubes on substrates. Hydrocarbon or oxyhydrocarbon mixtures were used as the carbon source. Hot electrons in the microwave plasma at temperatures exceeding 10,000C provided a means of dissociating the vapor or gas feedstock, heating the substrate, and allowing gas species to react in the gas phase as well as on the surface of the substrate leading to the deposition of desired carbon coatings. A high vacuum chamber was used to characterize the electron emission properties of these carbon nanotube coatings using a one-millimeter diameter tungsten rod with a hemispherical tip as the anode while the carbon nanotube coatings served as the cathode. The current-voltage characteristics of the carbon nanotube coatings were measured and used for calculating the electric field at which electron emission turned on as well as calculating the field enhancement factor of the carbon nanotubes. Field emission of electrons from carbon nanotubes starting from an electric field lower than 1 volt per micrometer has been achieved.

Hot-Filament Assisted Fabrication of Carbon-Nanotube Electron Emitters

2000 ◽  
Vol 621 ◽  
Author(s):  
Yonhua Tzeng ◽  
Chao Liu ◽  
Zheng Chen
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Electron Emission ◽  
High Vacuum ◽  
Field Enhancement ◽  
Current Voltage ◽  
Electron Emitters ◽  
Hot Filament ◽  
Field Emission Of Electrons

ABSTRACTA hot-filament CVD reactor was used for the deposition of carbon nanotubes on substrates. Hydrocarbon or oxyhydrocarbon mixtures were used as the carbon source. Hot filaments at temperatures exceeding 2000C provided a means of dissociating the vapor or gas feedstock, heating the substrate, and allowing gas species to react in the gas phase as well as on the surface of the substrate leading to the deposition of desired carbon coatings. A high vacuum chamber was used to characterize the electron emission properties of these carbon nanotube coatings using a one-millimeter diameter tungsten rod with a hemispherical tip as the anode while the carbon nanotube coatings served as the cathode. The current-voltage characteristics of the carbon nanotube coatings were measured and used for calculating the electric field at which electron emission turned on as well as calculating the field enhancement factor of the carbon nanotubes. Field emission of electrons from carbon nanotubes starting from an electric field of as low as 1-2 volts per micrometer was achieved.

scholarly journals Investigation of changes in field electron emission characteristics of industrial fine-grained graphite when operated in an argon atmosphere up to 10–2 Pa

2021 ◽  
Vol 2064 (1) ◽  
pp. 012107
Author(s):  
A S Chepusov ◽  
A A Komarskiy ◽  
S R Korzhenevskiy
Keyword(s):  
Electric Field ◽  
Electron Emission ◽  
Field Enhancement ◽  
Field Electron Emission ◽  
Emission Properties ◽  
Fine Grained ◽  
Cold Cathodes ◽  
Field Electron ◽  
Current Voltage ◽  
Technical Vacuum

Abstract Studying of field electron emission properties of carbon cathodes operating under technical vacuum conditions is a promising scientific field. Massive cathode made of commercial fine-grained graphite of MG (Russian abbreviation) grade is being investigated. Experiments on obtaining current-voltage characteristics and long-term testing are being carried out. The emitter made of fine-grained graphite demonstrates good emission properties under technical vacuum conditions. Carbon cathode is capable of operating at pressures up to 2×10–2 Pa. Increased pressure in the vacuum chamber leads to deterioration of cathode emission properties. Electric field enhancement factors were calculated for all stages of studies. Analysis of experimental data demonstrates decrease in enhancement factor due to ion bombardment of cathode surface during exploitation. This results in higher electric field for operation of investigated graphite cold cathodes.

scholarly journals Optically Induced Field-Emission Source Based on Aligned Vertical Carbon Nanotube Arrays

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1810
Author(s):  
Mengjie Li ◽  
Qilong Wang ◽  
Ji Xu ◽  
Jian Zhang ◽  
Zhiyang Qi ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Electric Field ◽  
Field Emission ◽  
Field Enhancement ◽  
Absorption Efficiency ◽  
Photon Absorption ◽  
Nanotube Arrays ◽  
Carbon Nanotube Arrays ◽  
Induced Field ◽  
Optically Induced

Due to the high field enhancement factor and photon-absorption efficiency, carbon nanotubes (CNTs) have been widely used in optically induced field-emission as a cathode. Here, we report vertical carbon nanotube arrays (VCNTAs) that performed as high-density electron sources. A combination of high applied electric field and laser illumination made it possible to modulate the emission with laser pulses. When the bias electric field and laser power density increased, the emission process is sensitive to a power law of the laser intensity, which supports the emission mechanism of optically induced field emission followed by over-the-barrier emission. Furthermore, we determine a polarization dependence that exhibits a cosine behavior, which verifies the high possibility of optically induced field emission.

Hydrogenated carbon nanotube-based spin caloritronics

2017 ◽  
Vol 19 (32) ◽  
pp. 21507-21513 ◽  
Author(s):  
Hong-Li Zeng ◽  
Yan-Dong Guo ◽  
Xiao-Hong Yan ◽  
Jie Zhou
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Gate Voltage ◽  
Seebeck Effect ◽  
Partial Hydrogenation ◽  
Spin Caloritronics ◽  
Spin Seebeck Effect ◽  
Or Gate

The spin-Seebeck effect (SSE) in linearly hydrogenated carbon nanotubes (CNTs) is realized, where partial hydrogenation makes CNTs acquire magnetism. Moreover, an odd–even effect of the SSE is observed, and the even cases could be used as spin-Seebeck diodes, without the need for an electric field or gate voltage.

Metallic Nanowires From Carbon Nanotube Building Blocks: The Effect of Atomic Defects on the Nanotube Influencing Nanowire Growth

2003 ◽  
Author(s):  
B. Panchapakesan ◽  
Kousik Sivakumar ◽  
Shaoxin Lu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Building Blocks ◽  
Model Systems ◽  
Initial Surface ◽  
Sensors And Actuators ◽  
Platinum Nanowires ◽  
Defect Sites ◽  
Current Densities

Manipulation and control of matter at the nano- and atomic level are crucial for the success of nano-scale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable to build electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires has been fabricated using this approach due to its applications in chemical sensing sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. The electric field assisted technique allows the deposition of metals with high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes. The thickness and the growth of the nanowires was altered by inducing defects on the initial surface of the nanotubes that affected the local current densities and electrochemical reduction of silver and platinum on those defect sites. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm-100 nm in diameter. Relatively higher metal deposition was achieved in defect related sites or places where the nanotubes criss-crossed each other, due to the high current densities in these sites. The present technique is versatile and enables the fabrication of host of different types of metallic and semiconduting nanowires using carbon nanotube templates for nanoelectronics and myriad of sensor applications. Further, nanowires can also serve as model systems for studying quantum size effects in these dimensions.

Highly Organized Carbon Nanotube-PDMS Hybrid System for Multifunctional Flexible Devices

2007 ◽  
Author(s):  
Yung J. Jung ◽  
Laila Jaber-Ansari ◽  
Xugang Xiong ◽  
Sinan Mu¨ftu¨ ◽  
Ahmed Busnaina ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Fields ◽  
Composite Structures ◽  
Field Enhancement ◽  
Chemical Vapor ◽  
Casting Process ◽  
Dip Coating ◽  
Network Architectures ◽  
Multiwalled Carbon

We will present a method to fabricate a new class of hybrid composite structures based on highly organized multiwalled carbon nanotube (MWNT) and singlewalled carbon nanotube (SWNT) network architectures and a polydimethylsiloxane (PDMS) matrix for the prototype high performance flexible systems which could be used for many daily-use applications. To build 1–3 dimensional highly organized network architectures with carbon nanotubes (both MWNT and SWNT) in macro/micro/nanoscale we used various nanotube assembly processes such as selective growth of carbon nanotubes using chemical vapor deposition (CVD) and self-assembly of nanotubes on the patterned trenches through solution evaporation with dip coating. Then these vertically or horizontally aligned and assembled nanotube architectures and networks are transferred in PDMS matrix using casting process thereby creating highly organized carbon nanotube based flexible composite structures. The PDMS matrix undergoes excellent conformal filling within the dense nanotube network, giving rise to extremely flexible conducting structures with unique electromechanical properties. We will demonstrate its robustness under large stress conditions, under which the composite is found to retain its conducting nature. We will also demonstrate that these structures can be directly utilized as flexible field-emission devices. Our devices show some of the best field enhancement factors and turn-on electric fields reported so far.

Electric field enhancement in field-emission cathodes based on carbon nanotubes

2010 ◽  
Vol 55 (2) ◽  
pp. 289-295 ◽  
Author(s):  
M. D. Bel’skii ◽  
G. S. Bocharov ◽  
A. V. Eletskii ◽  
T. J. Sommerer
Keyword(s):  
Carbon Nanotubes ◽  
Electric Field ◽  
Field Emission ◽  
Field Enhancement ◽  
Electric Field Enhancement ◽  
Field Emission Cathodes

Field Electron Emission from Carbon Nanotube Films on Diamond Films

2005 ◽  
Vol 475-479 ◽  
pp. 3587-3590
Author(s):  
K.J. Liao ◽  
W.L. Wang ◽  
Y.T. Wang ◽  
J.W. Lu ◽  
X.L. Sun
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Field Emission ◽  
Electron Emission ◽  
Diamond Films ◽  
Chemical Vapour ◽  
Polycrystalline Diamond ◽  
Field Electron Emission ◽  
Field Electron ◽  
Nanotube Films

The field electron emission from carbon nanotube films on polycrystalline diamond films was investigated. The carbon nanotubes and diamond films on Si substrates were prepared by a conventional hot filament chemical vapour deposition. The films obtained were characterized by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 10-6 Pa.. The experimental results showed that the field emission behaviours of carbon nanotubes/diomond films structure have greatly been improved as compared with carbon nanotubes and diamond films, respectively. A turn-on field of 1.0 V/µm and a maximum current of 500 µA at 1.5 V/µm were observed, which were lower than those of carbon nanotubes and polycrystalline diamond films, respectively. This improvement was attributed to the tip shape of sample surface, which provided an additional local increase in electric field at the tube ends.

Sign in / Sign up

Export Citation Format

Share Document