Engineers shrink memory device to one square nanometre

University of Texas-Austin engineers have created the smallest memory device yet which uses just a single atom to control its memory function.

 The project builds on a discovery from two years ago, when the same group of researchers created what was then the thinnest memory storage device, with a single atomic layer of thickness. This was nicknamed the “atomristor” by the research team.

They have now reduced the size of the memory device further, shrinking its cross-sectional area down to a single square nanometre.

“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 study,” said professor Deji Akinwande.

This miniaturisation required a grasp on the physics that allows for dense memory storage capability into these devices; defects, or holes in the material, provide the key to unlocking this capability: “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,” Akinwande said.

Although the researchers used monolayer molybdenum disulphide (MoS2) as the primary nanomaterial in this Nature Nanotechnology study, they expect that this could be applied to hundreds of related atomically thin materials.

Akinwande’s device belongs in the category of memristors. Memristors are a popular area of memory research, focused on electrical components with the ability to modify resistance states between two terminals without the need for a gate in the middle (non-volatile resistive switching). This allows for them to be miniaturised further than today’s memory devices, while retaining great storage capacity.

This memristor promises capacity of approximately 25TB per square centimetre: a memory density 100 times higher per layer compared with commercially available flash memory devices.

The race to miniaturise chips and other components is all about convenience and energy efficiency. Smaller processors allow for more compact computing devices, but also decreases their energy demands and increases capacity; this results in faster devices which draw less power to operate.

Pani Varanasi, program manager for the US Army Research Office, commented: “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 communications systems, and more.”