Eric Pop and colleagues at the University of Illinois report a new phase-change memory based on carbon nanotubes that could potentially replace flash memory, the current standard for nonvolative memory in everyday electronic devices such as smart phones, cameras, and USB sticks.Their work, published this week in Science, clears a major hurdle for phase-change memory devices by dramatically lowering the amount of heat needed to change phases, thereby lowering overall power consumption. Using narrow, highly-conductive carbon nanotubes, the researchers are able to create contacts on the order of 50 nm, which require 1/100th of the current to write flash memory.
Abstract: "Phase-change materials (PCMs) are promising candidates for nonvolatile data storage and reconfigurable electronics, but high programming currents have presented a challenge to realize low power operation. We controlled PCM bits with single-wall and small-diameter multi-wall carbon nanotubes. This configuration achieves programming currents as low as 0.5 μA (SET) and 5 μA (RESET), two orders of magnitude lower than state-ofthe- art devices. Pulsed measurements enable memory switching with very low energy consumption. Analysis of over one hundred devices finds that the programming voltage and energy are highly scalable, and could be below 1 V and single femtojoules per bit, respectively."
Xiong F, Liao A, Estrada D, and Pop E. Low-Power Switching of Phase-Change Materials with Carbon Nanotube Electrodes.Science Express 10 March 2011. DOI: 10.1126/science.1201938 .