Faster than Flash, Meltable Phase-Change Device Memory Is Finally in Production

It's been 40 years in the making. This week Samsung finally
announced they've kicked phase-change memory (PCM) into mass
production. In a nutshell, PCM stores information by melting
and freezing microscopic crystals. In gadgets like cell
phones, its frozen-in-place nature means lightning-fast
bootup times--instantaneous, even.

Part of PCM's current appeal is that it actually works better
the smaller it gets, unlike flash memory, which is the
current go-to for small devices. Since flash memory saves
data as small groups of electrons, the smaller the area you
have to work with, the fewer electrons will fit, thus making
the memory increasingly unstable.

PCM, on the other hand, actually benefits from shrinking, for
a simple reason: smaller crystals melt and freeze faster.
Matthias Wuttig, a physicist at RWTH Aachen University in
Germany, has developed PCM cells that can switch on in 19
nanoseconds.

The concept of PCM has been around since the 1960s, but has
presented persistent challenges for physicists. The first
attempts used crystals that required extremely high
temperatures in order to melt. By the time new crystal
materials that shifted forms at lower temps were developed,
gadget memory had already given way to the transistor (yes,
flash).

Samsung's PCM memory, for now, is only 512MB. But, Gregory
Atwood, a senior fellow at Numonyx Memory Solutions in
Switzerland, speculates in Nature that, as the demand for
smaller and smaller memory eclipses what flash can handle,
more time and attention will be paid to PCM and its potential
to succeed flash as the mobile go-to.