Materials science: Light makes memory faster

A new prototype random-access memory, which uses light for reading out information, is presented in this week’s online issue of Nature Communications. This memory has an exceptionally high write and read speed, a low energy consumption and good endurance making it a promising candidate in the quest for a “universal memory”.

The prototype is based on ferroelectrics. These materials have unique properties that have made them promising candidates for a new generation of random-access memory but reading out information has been a major problem. Previous efforts have only been able to achieve read-out by erasing the original information, which makes a rewrite step necessary. Junling Wang and colleagues present a solution to this problem by making use of the photovoltaic effect, which means that in ferroelectrics light can induce electric currents. While the writing step is performed as in regular ferroelectric random-access memories using a negative or positive voltage pulse, the information is read out by shining light on the sample. The light gives rise to a photocurrent whose polarization reveals whether a positive or negative voltage pulse had been applied in the writing step.

The authors construct a 16-cell prototype memory based on this idea, which compares well with other memory types in terms of energy consumption and endurance, but outperform them in speed.