We want to make transistors ever smaller to increase their energy efficiency and fit more of them on a chip. Scaling down transistors made of materials like sil

We want to make transistors ever smaller to increase their energy efficiency and fit more of them on a chip. Scaling down transistors made of materials like silicon hits limits, as the distances become so small that electrons can leak through the materials. In a field effect transistor (FET), you have a channel and a gate. The channel is a bit like a bridge which can be raised and lowered as ships travel underneath. Ideally, electrons shouldn't be able to flow between the channel and the gate (falling off the bridge), and depending on the voltage at the gate (position of the ship), the channel should range in resistance between zero (completely open; transistor is on) and infinity (completely closed; transistor is off). In a CNTFET, the channel is replaced with a carbon nanotube. The nanotube channel is very good at keeping the current carriers (electrons) inside, and so leakage is small. Additionally, nanotubes are very good at carrying current. To use the bridge analogy, the CNTFET has a bridge that is very wide, and so allows lots of people across, and has high walls such that the people don't fall in the water or onto the ship.