Team proves molecular data storage possible
—These stories appeared in SCOPE, the magazine of the College of Physical and Mathematical Sciences at NCSU, Spring/Summer 2004 issue
In the ongoing quest to create computing devices that are both incredibly small and incredibly powerful, scientists-envisioning a future beyond the limits of traditional semiconductors-have been working to use molecules for information storage and processing.
Until now, researchers were skeptical that such molecular devices could survive the rigors of real-world manufacturing and use, which involve high temperatures and up to one trillion operational cycles. But scientists at NC State and University of California-Riverside have demonstrated that molecular memories are indeed both durable and practical-a finding that could spur development of the technology.
The scientists' results were described in the Nov. 28 issue of the journal Science. Dr. Jonathan S. Lindsey, Glaxo Distinguished University Professor of Chemistry at NC State and one of the paper's authors, said the team was faced with a very basic problem. "If molecular materials can't compete against semiconductor materials under the rigorous conditions of the real world," he said, "then trying to implement them in electronic devices would be pointless. Because our goal is to develop molecule-based memory devices, we first had to test their durability and stability."
The team attached porphyrins-disk-shaped organic molecules-with specific electronic properties to an electroactive surface, storing information in the form of the molecules' positive charges.
After a series of tests, the scientists found that the resulting molecular memories were "extremely robust" and offered clear advantages over traditional semiconductor-based technology.
In addition, their testing showed that such molecule-based information-storage devices meet the processing and operating challenges required for use in electronic devices. In particular, the molecules are stable under extremes of temperature (400°C) and large numbers of read-write cycles (1 trillion).
That demonstrated stability indicates that these molecular structures can be adapted to current semiconductor fabrication technology and operated under conditions required for a practical device.
By establishing the practicality of molecular memories, says Lindsey, the findings should help eliminate doubts about the role of organic materials in electronic devices.
"There is a perception that organic molecules are fragile," Lindsey said. "The critical question has been whether, given the high temperatures and other stresses of production and use, any molecule-based devices could meet functionality standards. I believe our research has laid this question to rest, and demonstrated that appropriately chosen molecules can readily function in practical devices."
That knowledge, he said, should speed development of molecule-based electronics, which promise smaller, faster and far more powerful computers and other applications.
The UC-Riverside team is led by Professor David F. Bocian (Chemistry, '72). The research was funded by ZettaCore Inc. and the Defense Advanced Research Projects Agency (DARPA) Moletronics Program.
This illustration, prepared by NC State design student Troy Barber, represents the immense amount of information researchers believe could be stored in a memory cube system using molecular data storage technology. The current contents of the Library of Congress could be stored in 50 to 100 1-cm cubes. Carol M. Highsmith Photography, Inc. provided the photograph portion of the illustration.
Kimberly-Clark technology boosts molecular memory research
Dr. Jonathan S. Lindsey and his graduate students will benefit from technology and patents recently donated by Kimberly-Clark Worldwide Inc. The company's gift includes porphyrin synthesis technology and a related patent. The gift comes with Kimberly-Clark's internal research records, research samples and technical assistance, along with $200,000 in funding to support development of the donated technology.
Porphyrins are naturally occurring compounds, such as heme and chlorophyll. The porphyrin derivatives used in information storage are prepared synthetically. The Kimberly- Clark technology significantly improves the synthetic process, creating possibilities for commercial applications.
Lindsey described the donated technology as "a significant contribution to our ongoing study of compounds for molecular information storage."