Transferring the technology to fabrication facilities could go a long way toward filling that knowledge gap. “Once you have the fab, it’s a completely new game,” says Dmitri Strukov, professor of electrical and computer engineering at the University of California, Santa Barbara, who is developing memristors in his lab.
It could also help efforts to develop memristor logic circuits, says Richter. Memristors have been the subject of much interest because, in theory, they’re capable of activity that’s analogous to what happens in a synapse in the human brain. So far, however, all the experimental demonstrations of memristors have been accomplished by forcing them to behave more like transistors. Instead of switching between hundreds of states, these memristors have been made to switch between two states with a high and low resistance–a digital zero and one.
This week, in the journal Nature, Williams and colleagues reported a major step forward for memristor logic with the fabrication of circuits capable of full Boolean logic. The circuits are still digital, but Williams says his team has “shown that anything that can be calculated on silicon can be done with memristors,” and in a smaller space. Demonstrating digital logic with the devices is an important first step toward more exotic computing, says Strukov.
The memristor circuits reported in Nature are also capable of both memory and logic, functions that are done in separate devices in today’s computers. “Most of the energy used for computation today is used to move the data around” between the hard drive and the processor, says Williams. A future memristor-based device that provided both functions could save a lot of energy and help computers keep getting faster, even as silicon reaches its physical limits.
For now, though, the company will work to overcome potential manufacturing challenges that arise as it develops memristors for nonvolatile memory. Memristors are passive devices that must be built on top of traditional silicon transistors that serve to introduce power into the system. This complexity could be a hurdle, says Pinaki Mazumder, professor of electrical engineering and computer science at the University of Michigan. “As you introduce more [lithography] masks, it could have a negative effect on yields, because your chance of errors increases,” he says.
In spite of these challenges, Williams says it’s time for memristors to scale up. “Our lab results have been good, and it’s time to test memristors in the fab.”