Boffins have made optical transistors that can reach 4 TERAHERTZ

Resistance is useless

One of the reasons optics has the potential to be faster is that it doesn’t have the limitation of the RC time constant, also known as tau, where the capacitance of the resistor takes time to charge. Electrical transistors are limited by the RC delay time while the limiting mechanism for optical system is recombination time.

By eliminating RC delay there is scope for massive increases in clock speeds. The manufacturing process is similar to that used for traditional CMOS (Complementary metal-oxide semiconductor) chips. The transparent conducting oxides Perdue is working with are CMOS-compatible materials with low optical loss.

“Our materials are deposited using standard techniques, although there would need to be modification/optimisation for mass production," Kinsey informed The Register.

"Our oxide is deposited through pulsed laser ablation (i.e. a strong laser pulse literally blows off some of the material which travels across a chamber and sticks onto a substrate, not unlike how you would get splashed if you throw a ball hard enough into water), while our other materials for the switch are deposited through sputtering or chemical vapor deposition," he added.

"The last two are friendly to semiconductor fabrication facilities but the former is not. We would likely need to modify this to another process for mass production," he added.

By using AZO plasmonic oxide, the boffins reckon they could speed up switching in optical applications ten fold, and claim such an application is around five years away.

Kinsey cautions that something as advanced as a processor is at least two decades away, so while a 1,000-fold increase in processor power sounds a lot, it’s not when considered over the kind of timescales we are talking.

In fact, Moore's Law would extrapolate out to more than an eight thousand fold increase in the same time period. ®