Joined: 16 Mar 2004
|Posted: Wed Mar 21, 2007 12:19 pm Post subject: Carbon nanotubes for high performance sources
|Within the context of the CANVAD project nanolithographically defined growth of aligned nanotubes has been accomplished, opening new avenues in the field of satellite ground communications.
Currently, microwave links between high power transmitters located on ground and satellites allow long-range telecommunications. The ever increasing traffic in telecommunications coupled with the saturation of currently available frequency bands has brought needs for new bands. Allocation at higher frequencies between 30-100GHz is expected to render existing technology unsuitable.
Urged by this the CANVAD project focused on developing cold cathodes that use Carbon Nano-Tubes (CNTs) for microwave vacuum devices. Unlike existing hot thermionic cathodes, the CNT-based cold cathodes may result to the fabrication of inexpensive and compact amplifiers able to operate at higher frequencies (30 - 100GHz).
To this end, arrays of identical and vertically-aligned CNTs were produced using an approach that combines various parameters. These included precise control of the size and the position of the catalyst dot by nanolithography as well as selection of a high temperature diffusion barrier for high yield and uniformity. Furthermore, growth parameters were optimised in order to obtain selective growth of nanotubes.
Project work resulted in the development of highly selective, environmentally friendly and preferential growth of individual carbon nanotubes at specified locations on a substrate. The nanotube structures that have been developed feature exceptionally high uniformity and can be exploited as high performance electron sources in various application fields.
Apart from microwave amplifiers, the carbon nanotube array prototypes can be used in various applications such as microscopy, lithography, holography and field emission displays. Further collaborations are sought with commercial partners interested in exploiting carbon nanotube electron source technology in their products.
This story was first posted on 21st November 2006.