Nonvolatile memory is already familiar as the basis for flash memory in thumb drives, but flash technology has essentially reached its size and performance limits. For several years, the industry has been hunting for a replacement.

RRAM could surpass flash in many key respects: It is potentially faster and less energy-intensive. It also could pack far more memory into a given space—its switches are so small that a terabyte could be packed into a space the size of a postage stamp. But RRAM has yet to be broadly commercialized because of technical hurdles that need addressing.

RRAM switches are flipped on and off by an electrical pulse that moves oxygen ions around, creating or breaking a conductive path through an insulating oxide. NIST research shows that shorter, less energetic pulses are more effective at moving the ions the right amount to create distinct on/off states, potentially minimizing the longstanding problem of state overlap that has kept RRAM largely in the R&D stage. Credit: Hanacek and Nminibapiel/NIST

One hurdle is its variability. A practical memory switch needs two distinct states, representing either a one or a zero, and component designers need a predictable way to make the switch flip. Conventional memory switches flip reliably when they receive a pulse of electricity, but we're not there yet with RRAM switches, which are still flighty.