A Vacuum Transistor Based on Field-Assisted Thermionic Emission from a Multiwalled Carbon Nanotube

Vacuum triodes have been scaled down to the microscale on a chip by microfabrication technologies to be vacuum transistors. Most of the reported devices are based on field electron emission, which suffer from the problems of unstable electron emission, poor uniformity, and high requirement for operating vacuum. Here, to overcome these problems, a vacuum transistor based on Field-Assisted thermionic emission from individual carbon nanotubes is proposed and fabricated using microfabrication technologies. The carbon nanotube vacuum transistor exhibits an ON/OFF current ratio as high as 10(4) and a subthreshold slope of ~4 V center dot dec(-1). The gate controllability is found to be strongly dependent on the distance between the collector electrodes and electron emitter, and a device with the distance of 1.5 mu m shows a better gate controllability than that with the distance of 0.5 mu m. Benefiting from Field-Assisted thermionic emission mechanism, electric field required in our devices is about one order of magnitude smaller than that in the devices based on field electron emission, and the surface of the emitters shows much less gas molecule absorption than cold field emitters. These are expected to be helpful for improving the stability and uniformity of the devices.

Automated summary

Researchers have successfully fabricated a vacuum transistor based on carbon nanotubes using microfabrication technologies, overcoming the issues of unstable electron emission, poor uniformity, and high vacuum requirement. The carbon nanotube vacuum transistor exhibits a high ON/OFF current ratio and good gate controllability.