Researchers engineer improvements of technology used in digital memory

November 24, 2014 by   Scott Schrage, University of Nebraska-Lincoln
Left to right, University of Nebraska-Lincoln scientists Alexei Gruverman, Alexander Sinitskii and Evgeny Tsymbal. Credit: Craig Chandler, University Communications

The improvements in random access memory that have driven many advances of the digital age owe much to the innovative application of physics and chemistry at the atomic scale.

Accordingly, a team led by University of Nebraska-Lincoln researchers has employed a Nobel Prize-winning material and common household chemical to enhance the properties of a component primed for the next generation of high-speed, high-capacity RAM.

The team, which published its findings in the Nov. 24 edition of the journal Nature Communications, engineered and tested improvements in the performance of a memory structure known as a ferroelectric tunnel junction.

The junction features a ferroelectric layer 100,000 times thinner than a sheet of paper, so thin that electrons can "tunnel" through it. This layer resides between two electrodes that can reverse the direction of its —the alignment of positive and negative charges used to represent "0" and "1" in binary computing—by applying electric voltage to it.

The researchers became the first to design a ferroelectric junction with electrodes made of graphene, a carbon material only one atom thick. While its extreme conductivity makes graphene especially suited for small-scale electronics, the authors' primary interest lay in how it accommodated nearly any type of molecule—specifically, ammonia—they placed between it and the ferroelectric layer.

A junction's polarity determines its resistance to tunneling current, with one direction allowing current to flow and the other strongly reducing it. The researchers found that their graphene-ammonia combination increased the disparity between these "on" and "off" conditions, a prized outcome that improves the reliability of RAM devices and allows them to read data without having to rewrite it.

"This is one of the most important differences between previous technology that has already been commercialized and this emergent ferroelectric technology," said Alexei Gruverman, a Charles Bessey Professor of physics who co-authored the study.

Ferroelectric materials naturally boast the quality of "non-volatility," meaning they maintain their polarization—and can hence retain stored information—even in the absence of an external power source. However, the infinitesimal space between the positive and in a tunnel junction makes maintaining this polarization especially difficult, Gruverman said.

"In all memory devices, there is a gradual relaxation, or decrease, of this polarization," he said. "The thinner the ferroelectric layer is, the more difficult it is to keep these polarization charges separate, as there is a stronger driving force in the material that tries to get rid of it."

Gruverman said the team's graphene-ammonia combination also shows promise for addressing this prevalent issue, significantly improving the stability of the junction's polarization during the study.

Explore further: Boosting microelectronics with a little liquid logic

More information: Nature Communications, www.nature.com/ncomms/2014/141 … full/ncomms6518.html

Related Stories

Boosting microelectronics with a little liquid logic

August 8, 2014

Certain titanium-based metal oxides can form a crystal structure known as perovskite that results in a subtle internal imbalance of electric charges. This imbalance gives the material the ability to flip between two 'ferroelectric' ...

Small and stable ferroelectric domains

March 28, 2011

Researchers are one step closer to figuring out a way to make nano-sized ferroelectric domains more stable, reports a new study in journal Science.

Using electron beams to encode data in nanocrystals

March 26, 2014

Ferroelectric materials have an intrinsic electrical polarization caused by a small shift in the position of some of their atoms that occurs below a critical point called the Curie temperature. This polarization can be switched ...

Recommended for you

Electron sandwich doubles thermoelectric performance

June 20, 2018

Researchers more than doubled the ability of a material to convert heat into electricity, which could help reduce the amount of wasted heat, and thus wasted fossil fuel, in daily activities and industries.

New study explores cell mechanics at work

June 19, 2018

It's a remarkable choreography. In each of our bodies, more than 37 trillion cells tightly coordinate with other cells to organize into the numerous tissues and organs that make us tick.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.