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Gehan A J Amaratunga

Publications and source records attributed to Gehan A J Amaratunga.

3 recordsLinked to original sources
PubMed2005

Microwave devices: carbon nanotubes as cold cathodes.

To communicate, spacecraft and satellites rely on microwave devices, which at present are based on relatively inefficient thermionic electron sources that require heating and cannot be switched on instantaneously. Here we describe a microwave diode that uses a cold-cathode electron source consisting of carbon nanotubes and that operates at high frequency and at high current densities. Because it weighs little, responds instantaneously and has no need of heating, this miniaturized electron source should prove valuable for microwave devices used in telecommunications.

Journal Article↗
PubMed2005

Achieving high-current carbon nanotube emitters.

When a carbon nanotube emitter is operated at high currents (typically above 1 microA per emitter), a small voltage drop ( approximately few volts) along its length or at its contact generates a reverse/canceling electric field that causes a saturation-like deviation from the classical Fowler-Nordheim behavior with respect to the applied electric field. We present a correction to the Fowler-Nordheim equation to account for this effect, which is experimentally verified using field emission and contact electrical measurements on individual carbon nanotube emitters. By using rapid thermal annealing to improve both the crystallinity of the carbon nanotubes and their electrical contact to the substrate, it is possible to reduce this voltage drop, allowing very high currents of up to 100 microA to be achieved per emitter with no significant deviation from the classical Fowler-Nordheim behavior.

Journal Article↗