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1/3/11

Field specific properties of CNT

Electrical conductivity

Carbon nanotubes can form films that are highly electrically conductive and completely transparent looking like few layers of endless carbon nanotube ropes of about 50 nanometers thick and is very porous. Due to ideal conductivity it is used for multiple types such as touch screens which have applications in display terminals, games, portable computers, cell phones, personal digital assistants, touch screens, large-area transparent conductor, including LCD displays, plastic solar cells, and organic LED lighting, and many others.
CNT-based transparent conductive films are used in the touch panel, display, and solar industries. It is applied as a replacement for the brittle and expensive indi3um tin oxide (ITO) coated films currently used in touch screens, LCD displays, solar cells, and solid state (OLED) lighting. The existing market for ITO is approximately $1 billion for the material alone, not including its deposition. Indium tin oxide is rapidly becoming scarce and increasingly expensive and hence there is a requirement for low cost solutions and integration of ITO components into products such as LCD displays requires an expensive process that is complicated by ITO's incompatibility with many chemicals used in the display manufacturing process.
Semi conducting property
The semi conducting properties of carbon nanotubes are used to create printable transistors with extremely high performance. Nanotubes also prove to be useful additives to polymer based TFTs and help to overcome some of the shortcomings of those devices. Beyond their performance, such devices are compatible with solution-based printing techniques, which enable dramatic cost savings in such devices as LCDs and OLED-based displays.
Field Emitting property
Carbon nanotubes are the best field emitters of any known material due to their high electrical conductivity, and the unbeatable sharpness of their tip. If the tip is placed close to another electrode and a small voltage is applied between the tube and electrode, a large electric field builds up near the tip of the tube and sharper tip gives a large the electric field in the range of a millions of volts per centimeter. Even with only a few volts applied to an electrode a few microns away from the nanotube tip it can pull a substantial number of electrons out of the tip. As cold cathode electron emitters, carbon nanotube films have been shown to be capable of emitting extremely stable current of more than 4 Amperes per square centimeter. The high current density, low turn-on and operating voltage, and steady, long-lived behavior make carbon nanotubes ideal field emitters for this application in field-emission flat-panel displays. Other applications include: high-resolution x-ray sources, general cold-cathode lighting sources, high-performance microwave tubes, lightning arrestors, and electron microscope cathodes.
Thermal conductivity
Nanotubes give a solution to thermal management problems for the semiconductor industry. As more and more transistors are packed on chips, micro processors are getting hotter and noisier. Due to very high thermal conductivity nanotubes are used as heat sinks. Also due to the unique conducting and semi conducting properties, devices based on individual carbon nanotubes may serve to replace existing silicon devices and can also used to replace copper interconnects in integrated circuits.

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