Researchers from the Universities of Manchester and Nottingham developed a new ultra-fast bi-stable graphene transistor. They say that such transistors may enable new medical imaging and security devices.
A bi-stable transistor means that it can spontaneously switch between two electronic states. This new device is made from two layers of graphene separated by a boron nitride insulating layer. By applying a small voltage, you can tune the electron clouds in the graphene layers which induces the electrons so they move at high speed between the layers (by quantum tunneling over the thin insulating layer). This emits high-frequency electromagnetic waves (in the range between radar and infra-red).