Researchers are developing a new type of computer memory
that could be faster than the existing commercial memory and use far less power
than flash memory devices.
The technology combines silicon nanowires with a
“ferroelectric” polymer, a material that switches polarity when electric
fields are applied, making possible a new type of ferroelectric transistor.
“It’s in a very nascent stage,” says doctoral
student Saptarshi Das, who is working with Joerg Appenzeller, a professor of
electrical and computer engineering and scientific director of nanoelectronics
at Purdue’s Birck Nanotechnology Center.
The ferroelectric transistor’s changing polarity is read
as 0 or 1, an operation needed for digital circuits to store information in
binary code consisting of sequences of ones and zeroes.
The new technology is called FeTRAM, for ferroelectric
transistor random access memory.
“We’ve developed the theory and done the experiment
and also showed how it works in a circuit,” he says.
Findings are detailed in a research paper that appeared in
The FeTRAM technology has nonvolatile storage, meaning it
stays in memory after the computer is turned off. The devices have the
potential to use 99% less energy than flash memory, a non-volatile computer
storage chip and the predominant form of memory in the commercial market.
“However, our present device consumes more power
because it is still not properly scaled,” Das says. “For future
generations of FeTRAM technologies one of the main objectives will be to reduce
the power dissipation. They might also be much faster than another form of
computer memory called SRAM.”
The FeTRAM technology fulfills the three basic functions
of computer memory: to write information, read the information, and hold it for
a long period of time.
“You want to hold memory as long as possible, 10 to
20 years, and you should be able to read and write as many times as
possible,” Das says. “It should also be low power to keep your laptop
from getting too hot. And it needs to scale, meaning you can pack many devices
into a very small area. The use of silicon nanowires along with this
ferroelectric polymer has been motivated by these requirements.”
The new technology also is compatible with industry
manufacturing processes for complementary metal oxide semiconductors, or CMOS,
used to produce computer chips. It has the potential to replace conventional
A patent application has been filed for the concept.
The FeTRAMs are similar to state-of-the-art ferroelectric
random access memories, FeRAMs, which are in commercial use but represent a
relatively small part of the overall semiconductor market. Both use
ferroelectric material to store information in a nonvolatile fashion, but
unlike FeRAMS, the new technology allows for nondestructive readout, meaning
information can be read without losing it.
This non-destructive readout is possible by storing
information using a ferroelectric transistor instead of a capacitor, which is
used in conventional FeRAMs.