Silicon oxide memories transcend a hurdle

Embedded diodes boost Rice University invention's potential as robust, roomy memory

2013-07-09

(Press-News.org) HOUSTON – (July 9, 2013) – A Rice University laboratory pioneering memory devices that use cheap, plentiful silicon oxide to store data has pushed them a step further with chips that show the technology's practicality.

The team led by Rice chemist James Tour has built a 1-kilobit rewritable silicon oxide device with diodes that eliminate data-corrupting crosstalk.

A paper on the new work appears this week in the journal Advanced Materials.

With gigabytes of flash memory becoming steadily cheaper, a 1k nonvolatile memory unit has little practical use. But as a proof of concept, the chip shows it should be possible to surpass the limitations of flash memory in packing density, energy consumption per bit and switching speed.

The technique is based on an earlier discovery by the Tour lab: When electricity passes through a layer of silicon oxide, it strips away oxygen molecules and creates a channel of pure metallic phase silicon that is less than five nanometers wide. Normal operating voltages can repeatedly break and "heal" the channel, which can be read as either a "1" or "0" depending upon whether it is broken or intact.

The circuits require only two terminals instead of three, as in most memory chips. The crossbar memories built by the Rice lab are flexible, resist heat and radiation and show promise for stacking in three-dimensional arrays. Rudimentary silicon memories made in the Tour lab are now aboard the International Space Station, where they are being tested for their ability to hold a pattern when exposed to radiation.

The diodes eliminate crosstalk inherent in crossbar structures by keeping the electronic state on a cell from leaking into adjacent cells, Tour said. "It wasn't easy to develop, but it's now very easy to make," he said.

The device built by Rice postdoctoral researcher Gunuk Wang, lead author of the new paper, sandwiches the active silicon oxide between layers of palladium. The silicon-palladium sandwiches rest upon a thin layer of aluminum that combines with a base layer of p-doped silicon to act as a diode. Wang's 32 x 32-bit test arrays are a little more than a micrometer deep with crossbar line widths of 10 to 100 micrometers for testing purposes.

"We didn't try to miniaturize it," Tour said. "We've already demonstrated the native sub-5-nanometer filament, which is going to work with the smallest line size industry can make."

The devices have proven to be robust, with a high on/off ratio of about 10,000 to 1, over the equivalent of 10 years of use, low-energy consumption and even the capability for multibit switching, which would allow higher density information storage than conventional two-state memory systems.

The devices dubbed "one diode-one resistor" (1D-1R) worked especially well when compared with test versions (1R) that lacked the diode, Wang said. "Using just the silicon oxide was not enough," he said. "In a (1R) crossbar structure with just the memory material, if we made 1,024 cells, only about 63 cells would work individually. There would be crosstalk, and that was a problem."

To prove the 1D-1R's capabilities, Wang isolated 3 x 3 grids and encoded ASCII letters spelling out "RICE OWLS" into the bits. Setting adjacent bits to the "on" state – usually a condition that leads to voltage leaks and data corruption in a 1R crossbar structure – had no effect on the information, he said.

"From the engineering side of this, integrating diodes into a 1k memory array is no small feat," Tour said. "It will be industry's job to scale this into commercial memories, but this demonstration shows it can be done."

INFORMATION:

Co-authors of the paper are Rice graduate student Adam Lauchner; postdoctoral researcher Jian Lin; Douglas Natelson, a professor of physics and astronomy and of electrical and computer engineering, and Krishna Palem, the Ken and Audrey Kennedy Professor of Computer Science and Electrical and Computer Engineering and a professor of statistics. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science at Rice.

The Boeing Corp. and the Air Force Office of Scientific Research funded the work.

Read the abstract at: http://dx.doi.org/10.1002/adma.201302047

This news release can be found online at: http://news.rice.edu/2013/07/09/silicon-oxide-memories-transcend-a-hurdle/

Related Materials:

Tour Group: http://www.jmtour.com

In situ imaging of the conducting filament in a silicon oxide resistive switch: http://www.nature.com/srep/2012/120131/srep00242/full/srep00242.html

Images for download:

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-1-web.jpg

A scanning electron microscope image shows details of a 1-kilobit crossbar memory array designed and built at Rice University using silicon oxide as the active element. (Credit: Tour Group/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-2-web.jpg

Rice University has built crossbar memory chips based on silicon oxide that show potential for next-generation 3-D memories for computers and consumer devices. (Credit: Tour Group/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-3-web.jpg

A diode made of silicon and aluminum makes a two-terminal memory cell of palladium and silicon oxide possible in new research by Rice University scientists. The nonvolatile cells show promise for a new generation of dense, reliable 3-D memory. (Credit: Tour Group/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-4-web.jpg

Rice University researcher Gunuk Wang wrote ASCII code for "RICE OWLS" into a new breed of silicon oxide-based memory chips developed at Rice. The technology behind the chips has potential to surpass the limitations of current flash memory commonly found in computers and consumer devices. (Credit: Tour Group/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-5-web.jpg

Rice University researcher Gunuk Wang holds a chip with four 1-kilobit silicon oxide-based memories. Wang added diodes to each bit to prevent data-corrupting crosstalk between individual memory cells. (Credit: Jeff Fitlow/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-6-web.jpg

One-kilobit memory chips based on silicon oxide have the potential to surpass the limitations of flash memory in packing density, energy consumption per bit and switching speed, according to researchers at Rice University. The latest chips have embedded diodes that prevent data-corrupting crosstalk between individual memory cells. (Credit: Jeff Fitlow/Rice University)

http://news.rice.edu/wp-content/uploads/2013/06/0701_MEMORY-7-web.jpg

Rice University postdoctoral researcher Gunuk Wang, left, and chemist James Tour and their team have developed working 1-kilobit memory chips that use silicon oxide as the active element. (Credit: Jeff Fitlow/Rice University)

ELSE PRESS RELEASES FROM THIS DATE:

Newly identified bone marrow stem cells reveal markers for ALS

2013-07-09

Amyotrophic Lateral Sclerosis (ALS) is a devastating motor neuron disease that rapidly atrophies the muscles, leading to complete paralysis. Despite its high profile — established when it afflicted the New York Yankees' Lou Gehrig — ALS remains a disease that scientists are unable to predict, prevent, or cure. Although several genetic ALS mutations have been identified, they only apply to a small number of cases. The ongoing challenge is to identify the mechanisms behind the non-genetic form of the disease and draw useful comparisons with the genetic forms. Now, using ...

Did Neandertals have language?

2013-07-09

Fast-accumulating data seem to indicate that our close cousins, the Neandertals, were much more similar to us than imagined even a decade ago. But did they have anything like modern speech and language? And if so, what are the implications for understanding present-day linguistic diversity? The MPI for Psycholinguistics researchers Dan Dediu and Stephen C. Levinson argue in their paper in Frontiers in Language Sciences that modern language and speech can be traced back to the last common ancestor we shared with the Neandertals roughly half a million years ago. The Neandertals ...

5D optical memory in glass could record the last evidence of civilization

2013-07-09

Using nanostructured glass, scientists at the University of Southampton have, for the first time, experimentally demonstrated the recording and retrieval processes of five dimensional digital data by femtosecond laser writing. The storage allows unprecedented parameters including 360 TB/disc data capacity, thermal stability up to 1000°C and practically unlimited lifetime. Coined as the 'Superman' memory crystal, as the glass memory has been compared to the "memory crystals" used in the Superman films, the data is recorded via self-assembled nanostructures created in ...

Method to improve blood supply to engineered replacement tissues

2013-07-09

New Rochelle, NY -- Next-generation hydrogels can form synthetic scaffolds to support the formation of replacement tissues and organs in the emerging area of regenerative medicine. Embedding peptides into the hydrogels stimulates the growth of essential microvascular networks to ensure a good blood supply. Novel, cutting-edge technology in which hydrogels functionalized with laminin-derived peptides were transplanted in a mouse cornea and were shown to support cell growth and blood vessel formation is described in an article in BioResearch Open Access, a peer-reviewed open ...

Wildfires may contribute more to global warming than previously predicted

2013-07-09

LOS ALAMOS, N.M., July 9, 2013—Wildfires produce a witch's brew of carbon-containing particles, as anyone downwind of a forest fire can attest. A range of fine carbonaceous particles rising high into the air significantly degrade air quality, damaging human and wildlife health, and interacting with sunlight to affect climate. But measurements taken during the 2011 Las Conchas fire near Los Alamos National Laboratory show that the actual carbon-containing particles emitted by fires are very different than those used in current computer models, providing the potential for ...

Robotic ultrasound gives surgeon more direct control in mapping and removing kidney cancers

2013-07-09

DETROIT – While the use of ultrasound to identify tumors during kidney cancer surgery is gaining acceptance, a research team at Henry Ford Hospital has successfully taken it a step further by showing an added benefit when the procedure is done robotically. Simply put, the kidney surgeon who performs the ultrasound robotically has direct control over the painstaking procedure instead of having to rely on an assistant for part of the task. The researchers compared the robotic ultrasound probe to the same procedure using a laparoscopic ultrasound probe, which requires an ...

Promise and caution shown in ongoing research into stem cell treatment of strokes

2013-07-09

DETROIT – While stem-cell therapy offers great promise for the treatment of stroke, much research remains to be done to show its long-term effectiveness and to understand the potential for dangerous side effects. These are the conclusions drawn by Henry Ford Hospital neurologists Jing Zhang, M.D., Ph.D., and Michael Chopp, Ph.D., scientific director of the Henry Ford Hospital Neuroscience Institute, in a review of their own and other current research into the next-generation treatment of one of the leading causes of death and disability around the world. The article has ...

July/August 2013 Annals of Family Medicine tip sheet

2013-07-09

The Need for Discussion About Prostate Cancer Screening Choices, Optimizing Shared Decision Making Three research studies and an accompanying editorial address the importance of shared decision making around prostate cancer screening. Although prostate cancer is among the most common cancers among men in the United States, the value of screening for prostate cancer by measuring prostate-specific antigen levels remains highly controversial because screening can lead to invasive procedures and treatments that in turn can cause substantial harm. Because such harms may outweigh ...

Fixed payments not a barrier to quality of care in HMOs, study finds

2013-07-09

Ever since the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, the number of enrollees in Medicare Advantage, Medicare's managed care program, has jumped from 5.3 million to 14.4 million in 2013. While most individuals in Medicare opt for the traditional, fee-for-service benefit, many more are enrolling in HMOs and other managed care options. This dynamic heightens the importance of a question health care professionals and policymakers have been asking for many years: Does the system of fixed reimbursement inherent to HMOs and other forms of health ...

Annals of Internal Medicine tip Sheet for 9 July 2013

2013-07-09

1. Task force finds insufficient evidence to recommend for or against screening for primary open-angle glaucoma The United States Preventive Services Task Force (USPSTF) found insufficient evidence to assess the balance of benefits and harms of screening for primary open-angle glaucoma (POAG) in adults. Glaucoma is an acquired degeneration of the optic nerve that is the second most common cause of blindness worldwide. Open-angle is the most common type of glaucoma where an increase in pressure on the optic nerve occurs slowly over time. The goal of potential screening ...

One of the largest studies on preterm birth finds a maternal biomarker test significantly reduces neonatal morbidities and improves neonatal outcomes

One of the largest studies of its kind finds early intervention with iron delivered intravenously during pregnancy is a safe and effective treatment for anemia

New Case Western Reserve University study identifies key protein’s role in psoriasis

[Press-News.org] Silicon oxide memories transcend a hurdle
Embedded diodes boost Rice University invention's potential as robust, roomy memory

Silicon oxide memories transcend a hurdle

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: