Nanotubes Reduce Energy Drain in Digital Memory

Carbon nanotube illustration (National Science Foundation)

University of Illinois engineers have developed a form of ultra-low-power digital memory that is faster and uses 100 times less energy than similar available memory. The student-faculty team at the school’s Champaign campus published its findings online in this week’s Science Express (paid subscription required).

Flash memory in mobile devices today stores bits — 0/1 or on/off data codes — as charges, which requires high programming voltages and is relatively slow. Industry has been exploring faster, but higher power phase-change materials (PCM) as an alternative. In PCM memory a bit is stored in the resistance of the material, which is switchable from “on” to “off” or vice-versa.

The team led by engineering professor Eric Pop lowered the power per bit to 100 times less than existing PCM memory by reducing the size of the storage media. Rather than the industry standard metal wires, Pop’s group used carbon nanotubes only a few nanometers in diameter — some 10,000 times smaller than a human hair (1 nanometer equals 1 billionth of a meter).

To create a bit, the researchers place a small amount of PCM in a nanoscale gap formed in the middle of a carbon nanotube. They can switch the bit “on” and “off” by passing small currents through the nanotube.

Nanotubes are not only electronic conductors, they are quite stable as well and do not degrade like metal wires. The PCM that functions as the actual bit is also immune to accidental erasure from a passing scanner or magnet.

The lower power drain from nanotube memory could translate into longer life and smaller size of batteries for electronic devices. It would also hasten the arrival of more feasible devices running on renewable energy, such as solar or hand-cranked power.

Read more: New Process Developed for Thin-Layered Nanomaterials

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