New computer memory could greatly improve performance and reduce energy use

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Researchers led by the University of Cambridge have developed a new computer memory design that could greatly improve performance and reduce the energy demands of internet and communications technologies.

Our data-hungry world has increased energy demands, making it ever more difficult to reduce carbon emissions. Artificial intelligence, internet usage, algorithms, and other data-driven technologies are expected to consume nearly a third of global electricity in the next few years. This explosion in energy demands is largely due to shortcomings of current computer memory technologies.

Conventional memory devices are capable of two states – one or zero. This data is stored and processed in different parts of a computer system, so the data needs to be shuffled back between the two, which takes both energy and time.

A new type of technology known as resistive switching memory could be a potential solution to this problem of inefficient computer memory. Rather than flipping a bit of information into one of two possible states, this emerging form of computer memory can create a continuous range of states. Computer memory devices based on this principle would be capable of far greater density and speed.

“A typical USB stick based on the continuous range would be able to hold between ten and 100 times more information, for example,” said first author Dr. Markus Hellenbrand, from Cambridge’s Department of Materials Science and Metallurgy.

For their new study, researchers have developed a prototype resistive switching memory device based on hafnium oxide, an insulating material that is already used in the semiconductor industry. But, it’s challenging to use this material for resistive switching memory applications because it has no structure at the atomic level, with the hafnium and oxygen atoms randomly mixed.

However, the Cambridge researchers found that adding barium to thin films of hafnium oxide helped change that. When barium was put into the mix, some unusual structures formed perpendicular to the composite material’s hafnium oxide plane. These vertical barium-rich ‘bridges’ are highly structured and allow electrons to pass through them easily. At the point where these bridges meet the device contacts, an energy barrier was created, and the height of this barrier was controlled, which in turn changed the electrical resistance of the composite material, encoding 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.”

These hafnium oxide composites can self-assemble at low temperatures, unlike other composite materials, which require expensive high-temperature manufacturing methods. In addition, the material showed high levels of performance and uniformity, making them highly promising for next-generation memory applications. Because hafnium oxide is already widely used in the semiconductor industry, the researchers say it would be easy to integrate into existing manufacturing processes.

Larger feasibility studies on the materials will allow researchers to understand more clearly how high-performance structures form.

Journal reference:

  1. Markus Hellenbrand, Babak Bakhit, Hongyi Dou, Ming Xiao, Megan O. Hill, Zhuotong Sun, Adnan Mehonic, Aiping Chen, Quanxi Jia, Haiyan Wang, Judith L. MacManus-Driscoll. Thin-film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity. Science Advances, 2023; DOI: 10.1126/sciadv.adg1946
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