‘Invisibility’ the key to better electronics?

Inspired by cloaking mechanisms where light beams bend around an object and meet on the other side to make it appear invisible, the team applied this idea to the movement of electrons. The researchers modelled nanoparticles with a core of one material and a shell of another. But rather than bending around the object, the electrons pass through the particles. Their paths are bent first one way, then back again, so they return to the same trajectory they began with. In computer simulations, the concept appears to work. Now the team will try to build actual devices to see whether they perform as expected. "This was a first step, a theoretical proposal," said MIT graduate student Bolin Liao. "We want to carry on further research on how to make some real devices out of this strategy." While the initial concept was developed using particles embedded in a normal semiconductor substrate, the researchers would also like to see if the results can be replicated with other materials, such as two dimensional sheets of graphene, which might offer interesting additional properties. The researchers say the initial impetus was to optimise the materials used in thermoelectric devices, which produce an electrical current from a temperature gradient. These devices require both high electrical conductivity and low thermal conductivity which rarely coexist, but the team says its simulations show the electron cloaking material could meet these requirements unusually well. The concept could also lead to a new kind of switches for electronic devices, which operate by toggling between transparent and opaque to electrons, thus turning a flow of them on and off.