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NewswireToday - /newswire/ -
Honolulu, HI, United States, 09/01/2006 - Carbon nanotubes (CNTs) are considered the most promising material for field emitters and a practical example are CNTs as electron emitters for field emission displays (FED)..
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CNT emitters are generally fabricated by indirect growth methods such as screen-printing and electrophoresis. These methods show advantages in lowering the coating temperature and scale-up of the substrate size, but the direction of CNTs cannot be well controlled and a post-treatment process is generally necessary to enhance the performance of CNT emitters. In contrast to the indirect method, chemical vapor deposition (CVD) is a common technique for growing nanotubes directly on the substrate with the assistance of metallic catalysts. With the CVD method, CNTs can be grown at desired locations with a specified direction. However,most synthesis technologies such as conventional thermal CVD or plasma enhanced CVD are performed at temperatures over 500°C, which may restrict the application of CNTs on plastic substrates. Therefore, lowering the growth temperature for CNTs is one of the important directions for facilitating CNT applications.
Researchers in Taiwan demonstrated that CNTs can be synthesized on a cobalt coated silicon substrate using electron cyclotron chemical vapor deposition (ECR-CVD) and without intentionally heating the substrate. They fabricated vertical CNTs with microwave power as low as 300 W.
The ability to grow CNTs at low temperatures allows CNT emitters to be synthesized on glass and plastic substrates. Direct fabrication of well aligned CNT emitters on normal glass is cost effective for manufacturing CNT-FED, while growth of CNTs on plastics makes flexible CNT-FED possible. Short CNTs on the other hand can be applied to nanoscale electronic devices such as nanowire field effect transistors (FET) and are suitable candidates for nano composite materials.
Read the full article on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk LLC
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editor[.]nanowerk.com 
