Cambridge scientists have developed a new prototype for computer memory that could make for faster chips that could hold up to 100 times more data. The system is made up of barium bridges between films of a disordered material.
As powerful as current computer technology can be, there are a few hard limits to it. Data is encoded into just two states – one or zero. And this data is stored and processed in different parts of a computer system, so it needs to be shuttled back and forth, which consumes energy and time.
But an emerging form of computer memory, known as resistive switching memory, is designed to be far more efficient. Rather than flipping a bit of information into one of two possible states, this new kind of memory can create a continuous range of states. This is done by applying an electrical current to certain types of materials, which causes their electrical resistance to become either stronger or weaker. A broad spectrum of these slight differences in electrical resistance creates a series of possible states to store data.
“A typical USB stick based on continuous range would be able to hold between 10 and 100 times more information, for example,” said Dr. Markus Hellenbrand, first author of the study.
For the new study, the team developed a prototype of a resistive switching memory device made with a material called hafnium oxide, which is already in use in the semiconductor industry as an insulator. Normally it’s challenging to use for memory because it has no structure at the atomic level – its hafnium and oxygen atoms are randomly mixed together. But here, the Cambridge researchers found that adding an extra ingredient helped change that.
When barium was thrown into the mix, it formed vertical “bridges” between stacked thin films of hafnium oxide. Since these barium bridges are highly structured, electrons can travel through them easily. An energy barrier is created at the points where the bridges meet the device contacts, and the height of this barrier can be controlled which changes the electrical resistance of the overall material. That in turn is what encodes the data.
“This allows multiple states to exist in the material, unlike conventional memory which has only two states,” said Hellenbrand. “What’s really exciting about these materials is they can work like a synapse in the brain: they can store and process information in the same place, like our brains can, making them highly promising for the rapidly growing AI and machine learning fields.”
The researchers say that their device, using thin films of hafnium oxide connected by barium bridges, has a few advantages to help it along the path to commercialization. For one, these structures can self-assemble under relatively low temperatures, which is easier than the high-temperature manufacturing that many others need. Plus, the materials are already in wide use in the computer chip industry, so it should be easier to incorporate them into existing manufacturing techniques. Feasibility studies on the materials will allow the scientists to investigate how well they might work at larger scales.
The research was published in the journal Science Advances.
Source: Cambridge University
