The surface of a rewritable digital video disk is covered in a material that can reversibly switch between crystalline and amorphous phases when irradiated by a laser. An electronic memory based on such a phase-change material would have numerous advantages, including non-volatility. However, electronic phase-change memories have required high programming currents to generate the heat necessary for a phase transformation. Now, Eric Pop and colleagues at the University of Illinois at Urbana-Champaign have constructed an electronic phase-change memory that can be programmed with currents 100 times smaller than those required by state-of-the-art devices.
The key to the advance was reducing the volume of the active phase-change material. Gaps as small as 20 nm in width were created in carbon nanotubes with diameters of less than 6 nm, and then filled with a chalcogenide phase-change material. Voltages applied across the nanotubes resulted in large electric fields across these gaps, causing sufficient Joule heating to switch the chalcogenide from a resistive to a conducting state while drawing as little as 1 μA of current. Switching back to a resistive state took as little as 5 μA. This translated to a minimum energy per bit of 100 femtojoules, with the potential to scale to lower values for smaller gap sizes.
Rights and permissions
About this article
Cite this article
Current performance. Nature Nanotech (2011). https://doi.org/10.1038/nnano.2011.60
Published:
DOI: https://doi.org/10.1038/nnano.2011.60