How do wrap-around gate CNTFETs work?

[niklasR]

Hello,
I do my physics coursework about Graphene and carbon nanotubes. In this context i mainly have to talk about them replacing silicon in transistors like (MOS)FETs - Wrap-around gate CNTFETs

Homework Statement

I know how a standard silicium-MOSFET works, the is the source, and the drain and both are connected through the silicon-gate which only conducts if there is a voltage applied.
But I don't quite get how a CNTFT works. I have this, very simple image:

(by Popproject3, Wikimedia)
On the left hand we have the source, on the right the drain. The metal layer is the gate.

But, my questions:

1. What does the CNT stop from conducting when there is no voltage applied at the gate?
2. The dielectric layer does never conduct, so how the gate "tell" the CNT to conduct? Is it just the electromegnetic field around it? (I suppose I need an answer to question 1 to get an answer for that ;)

2. The attempt at a solution
A lot of thinking & reading, mainly on http://en.wikipedia.org/wiki/MOSFET" and other things.

Please don't spam the thread with "google it", or something, I DID google it and I haven't found helpful, understandable things.

I'm Lower Sixth.


PS: I'm German…

 

[NateD]

Answer: A carbon nanotube field effect transistor (CNTFET) is a type of field-effect transistor that utilizes a carbon nanotube as its channel instead of a semiconductor like silicon. In a CNTFET, the source and drain are connected by a single walled or multi-walled carbon nanotube. A metal gate wraps around the carbon nanotube and is separated from it by a thin dielectric layer. The gate voltage applied to the metal gate controls the current flow between the source and drain. When a positive voltage is applied to the gate, it creates an electric field that attracts electrons to the gate. This creates a "channel" of electrons that can then flow between the source and drain. When there is no voltage applied to the gate, the electric field does not exist, and so the channel between the source and drain is blocked, preventing the flow of current.