Researchers in Silicon Valley have managed to observe electrical switching that is thousands of times faster than transistors used in today's computer chips. Their work could lead to a better understanding of how transistors work at the atomic level and in turn help to enable more powerful computers.
An optical laser pulse (red streak from upper right) shatters the ordered electronic structure (blue) in an insulating sample of magnetite, switching the material to electrically conducting (red) in one trillionth of a second.
Transistors are semiconductor devices that act as simple on-off electrical switches. The number of transistors in a computer chip has a direct effect on its speed and power, so researchers are continually trying to make their transistors smaller and faster.
In work at the SLAC National Accelerator Laboratory in Menlo Park, California, researchers using an X-ray laser to discovered it takes just one trillionth of a second to switch between on and off states in a sample of magnetite, a type of mineral.
They hit each sample with a pulse of visible light from a laser, which caused the electronic structure of the material to rearrange itself. Immediately afterwards, they hit it with a burst from an ultrabright, ultrashort X-ray laser which revealed that the rearrangement had begun hundredths of quadrillionths of seconds after the initial pulse hit the sample.
The precise time for the switching from a non-conducting (off) state to a conducting (on) state was determined by varying the interval of the X-ray laser pulses.
"This breakthrough research reveals for the first time the 'speed limit' for electrical switching in this material," Roopali Kukreja, a materials science researcher at SLAC and Stanford University who is a lead author of the study, said in a statement.
Despite the research, chips made from magnetite aren't expected anytime soon. The research required the material to be cooled to minus 190 degrees Celcius, which makes it impractical for widespread commercial use.
But, using the research as a base, the team will go on to study more complex materials and applications at room temperature, a SLAC spokesman said. The hope is that increased knowledge of electrical switching in materials like magnetite will help scientists understand the switching inside materials such as silicon, which is used in current chips, or new hybrid materials that might offer improvements on silicon.
The research was published July 28 in Nature Materials. It was carried out with scientists in Germany, the Netherlands, Italy, Switzerland and other facilities in the U.S.
