Silicon Valley is undergoing a major shift, one which may require it to rethink its name. This is thanks in no small part to the efforts of a team based at Stanford that is seeking to create the first basic computer built around carbon nanotubes rather than silicon chips. In addition to changing how computers are built, this is likely to extend the efficiency and performance.
What’s more, this change may deal a serious blow to the law of computing known as Moore’s Law. For decades now, the exponential acceleration of technology – which has taken us from room-size computers run by punched paper cards to handheld devices with far more computing power – has depended the ability to place more and more transistors onto an individual chip.
The result of this ongoing trend in miniaturization has been devices that are becoming smaller, more powerful, and cheaper. The law used to describe this – though “basic rule” would be a more apt description – states that the number of transistors on a chip has been doubling every 18 months or so since the dawn of the information age. This is what is known as “Moore’s Law.”
However, this trend could be coming to an end, mainly because its becoming increasingly difficult, expensive and inefficient to keep jamming more tiny transistors on a chip. In addition, there are the inevitable physical limitations involved, as miniaturization can only go on for so long before its becomes unfeasible.
Carbon nanotubes, which are long chains of carbon atoms thousands of times thinner than a human hair, have the potential to be more energy-efficient and outperform computers made with silicon components. Using a technique that involved “burning” off and weeding out imperfections with an algorithm from the nanotube matrix, the team built a very basic computer with 178 transistors that can do tasks like counting and number sorting.
In a recent release from the university, Stanford professor Subhasish Mitra said:
People have been talking about a new era of carbon nanotube electronics moving beyond silicon. But there have been few demonstrations of complete digital systems using this exciting technology. Here is the proof.
Naturally, this computer is more of a proof of concept than a working prototype. There are still a number of problems with the idea, such as the fact that nanotubes don’t always grow in straight lines and cannot always “switch off” like a regular transistor. The Stanford team’s computer’s also has limited power due to the limited facilities they had to work with, which did not have access to industrial fabrication tools.
All told, their computer is only about as powerful as an Intel 4004, the first single-chip silicon microprocessor that was released in 1971. But given time, we can expect more sophisticated designs to emerge, especially if design teams have access to top of the line facilities to build prototypes.
And this research team is hardly alone in this regard. Last year, Silicon Valley giant IBM managed to create their own transistors using carbon nanotubes and also found that they outperformed the transistors made of silicon. What’s more, these transistors measured less than ten nanometers across, and were able to operated using very low voltage.
Similarly, a research team from Northwestern University in Evanston, Illinois managed to create something very similar. In their case, this consisted of a logic gate – the fundamental circuit that all integrated circuits are based on – using carbon nanotubes to create transistors that operate in a CMOS-like architecture. And much like IBM and the Standford team’s transistors, it functioned at very low power levels.
What this demonstrated is that carbon nanotube transistors and other computer components are not only feasible, but are able to outperform transistors many times their size while using a fraction of the power. Hence, it is probably only a matter of time before a fully-functional computer is built – using carbon nanotube components – that will supersede silicon systems and throw Moore’s Law out the window.