Breakthrough in transistor fabrication without semiconductors

Michigan Technological University scientists led by professor of physics Yoke Khin Yap have created a quantum tunneling device that acts like like an FET transistor and works at room temperature without using semiconducting materials.

The trick was to use boron nitride nanotubes (BNNTs) with quantum dots made from gold. When sufficient voltage is applied to the device, it switches from insulator to a conducting state. When the voltage is low or turned off, it reverts to its natural state as an insulator. There is no leakage current of electrons escaping from the gold dots into the insulating BNNTs, thus keeping the tunneling channel cool. In contrast, silicon is subject to leakage, which wastes energy in electronic devices and generates a lot of heat, limiting miniaturization of transistors.

Carpets of boron nitride nanotubes, which are insulators and highly resistant to electrical charge were grown on a substrate. Using lasers, quantum dots (QDs) of gold  are deposited as small as three nanometers across on the tops of the BNNTs, forming QDs-BNNTs. BNNTs are the perfect substrates for these quantum dots due to their small, controllable, and uniform diameters, as well as their insulating nature. BNNTs confine the size of the dots that can be deposited. Now if we applied biasing, electrons jumped very precisely from gold dot to gold dot, which is known as quantum tunneling.

Other people have made transistors that exploit quantum tunneling. However, those tunneling field effect transistors have only worked in low temperature. The gold islands have to be on the order of nanometers across to control the electrons at room temperature. If they are too big, too many electrons can flow.

For further reading
http://www.readcube.com/articles/10.1002/adma.201301339?