Silicon breakthrough could make key microwave technology much cheaper and better

Researchers using powerful supercomputers have found a way to generate microwaves with inexpensive silicon, a breakthrough that could dramatically cut costs and improve devices such as sensors in self-driving vehicles.
"Until now, this was considered impossible," said C.R. Selvakumar, an engineering professor at the University of Waterloo who proposed the concept several years ago.

High-frequency microwaves carry signals in a wide range of devices, including the radar units police use to catch speeders and collision-avoidance systems in cars.

The microwaves are typically generated by devices called Gunn diodes, which take advantage of the unique properties of expensive and toxic semiconductor materials such as gallium arsenide.

Whenvoltage is applied to gallium arsenide and then increased, the electrical current running through it also increases—but only to a certain point. Beyond that point, the current decreases, an oddity known as the Gunn effect that results in the emission of microwaves.

Lead researcher Daryoush Shiri, a former Waterloo doctoral student who nowworks atChalmers University of Technology in Sweden, used computational nanotechnology to show that the same effect could be achieved with silicon.
The second-most abundant substance on earth, silicon would be far easier to work with for manufacturing and costs about one-twentieth as much as gallium arsenide.