MoS2 as Nanomaterial of Smallest Atom-Memory Unit

Engineers at The University of Texas at Austin (UT Austin) use MoS₂ as the main nanomaterial to create the smallest atom-memory device in the world. Faster, smaller, smarter and more energy-efficient chips for everything from consumer electronics to big data to brain-inspired computing could soon be on the way after UT Austin creates the smallest memory device. In the process, the researchers figured out the physics dynamic that unlocks dense memory storage capabilities for these tiny devices.

The recently published research on Nature Nanotechnology was established two years ago, when researchers created the thinnest atom-memory storage device found at the time. In this new work, the researchers further reduced the size, reducing the cross-sectional area to only one square nanometer.

Getting a handle on the physics that packs dense memory storage capability into these devices enabled the ability to make them much smaller. Defects, or holes in the material, provide the key to unlocking the high-density memory storage capability.

Deji Akinwande, a professor in the Department of Electrical and Computer Engineering, said: "When a single additional metal atom goes into that nanoscale hole and fills it, it confers some of its conductivity into the material, and this leads to a change or memory effect."

Although they used molybdenum disulfide (also known as MoS₂) as the primary nanomaterial in their study, the researchers think the discovery could apply to hundreds of related atomically thin materials.

The race to make smaller chips and components is all about power and convenience. With smaller processors, you can make more compact computers and phones. But shrinking down chips also decreases their energy demands and increases capacity, which means faster, smarter devices that take less power to operate.

"The results obtained in this work pave the way for developing future-generation applications that are of interest to the Department of Defense, such as ultra-dense storage, neuromorphic computing systems, radio-frequency communication systems and more," said Pani Varanasi of the program, the manager of the US Army Research Office who funded this research.

The original device (called the "atomristor" by the research team) was at the time the thinnest memory storage device ever recorded, with a single atomic layer of thickness. But shrinking a memory device is not just about making it thinner but also building it with a smaller cross-sectional area.

Akinwand said: "The scientific holy grail for scaling is going down to a level where a single atom controls the memory function, and this is what we accomplished in the new research."

Akinwande's device falls under the category of memristors, a popular area of memory research, centered around electrical components with the ability to modify resistance between its two terminals without a need for a third terminal in the middle known as the gate. That means they can be smaller than today's atom-memory devices and boast more storage capacity.

This version of the memristor uses MoS₂ as the primary nanomaterial - developed using the advanced facilities at the Oak Ridge National Laboratory -- promises a capacity of about 25 terabits per square centimeter. That is 100 times higher memory density per layer compared with commercially available flash atom-memory devices.

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