• 09.24.13

This Is What Comes After Silicon Chips

Amazing research into carbon nanotubes gives us a hint of one future chip technology.

This Is What Comes After Silicon Chips

The problem with silicon chips is that we’ve gotten very good at making them. So very good that we’re approaching the limits of what we can do with the tech, prompting researchers to begin looking for “post-silicon” chip solutions. Now a team from Northwestern University in Evanston, Illinois has created something that gives us a hint what our next chip tech may be made of: carbon. They’ve created a logic device out of carbon nanotubes that works on phenomenally low power levels.


The NU team has managed to create a gate–the fundamental circuit that all integrated circuits are based on–using carbon nanotubes to create transistors that operate in a CMOS-like architecture. By combining these transistors in well-known configurations, they’ve been able to make inverter NAND and NOR gates, which basically allows them to create almost any circuit that’s already been dreamed of using traditional silicon-based chips.

CMOS has a power advantage over other chip architectures because in a steady-state condition, one of the two transistor types making up a gate is turned off, thereby drawing no power. When you add in the very low power consumed by the carbon nanotube transistors, you get a logic circuit that only needs 0.1 nanowatts in a steady state. At peak power consumption, when the circuit is switching from off to on for example, it needs just 10 nanowatts. That steady state power consumption is a lot less than traditional chip technology burns. Three orders of magnitude less, or one thousandth, which is an incredible reduction in the electrical energy needed to operate the chip, and this should lead to less waste heat being produced when the chip operates.

What NU has in fact demonstrated is an ultra low power carbon nanotube chip architecture. There are two possible upshots to this innovation when it’s integrated into a full-functioning chip. The first is that CPUs in mobile devices could consume much less power, perhaps running off battery or solar energy where before it would be impractical. The second is that more transistors could be included on the die of a chip inside a device like an iPhone without leading to too much heat generation or battery guzzling. Analysis of Apple’s new A7 chip, for example, suggests that Apple’s pulled off some clever trade-offs in the design to include smaller transistors…one billion of them. Part of the decision-making process will have had to be how much power the chip drew and wasted as heat (because you don’t want your iPhone to sear your skin), and though you can be clever with standard silicon chip design you’re not going to make a several-orders-of-magnitude change in power consumed.

And yes, it’s a fascinating thought that the same basic element that powered the industrial revolution may end up as a key component of the next revolution in computing power.

[Image: Flickr user Jiahui Huang]

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