As reported in a recent paper,* the device is a type of “non-volatile” memory, meaning stored information is not lost when the device is without power. So-called “flash” memory (used in digital camera memory cards, USB memory sticks, etc.) is a well-known example of electronic non-volatile memory. In this new device, nanowires are integrated with a higher-end type of non-volatile memory that is similar to flash, a layered structure known as semiconductor-oxide-nitride-oxide-semiconductor (SONOS) technology. The nanowires are positioned using a hands-off self-alignment technique, which could allow the production cost—and therefore the overall cost—of large-scale viable devices to be lower than flash memory cards, which require more complicated fabrication methods.
The researchers grew the nanowires onto a layered oxide-nitride-oxide substrate. Applying a positive voltage across the wires causes electrons in the wires to tunnel down into the substrate, charging it. A negative voltage causes the electrons to tunnel back up into the wires. This process is the key to the device’s memory function: when fully charged, each nanowire device stores a single bit of information, either a “0” or a “1” depending on the position of the electrons. When no voltage is present, the stored information can be read.
The device combines the excellent electronic properties of nanowires with established technology, and thus has several characteristics that make it very promising for applications in non-volatile memory. For example, it has simple read, write, and erase capabilities. It boasts a large memory window—the voltage range over which it stores information—which indicates good memory retention and a high resistance to disturbances from outside voltages. The device also has a large on/off current ratio, a property that allows the circuit to clearly distinguish between the “0” and “1” states.
Two advantages the NIST design may hold over alternative proposals for nanowire-based memory devices, the researchers say, are better stability at higher temperatures and easier integration into existing chip fabrication technology.* Q. Li, X. Zhu, H. Xiong, S.-M. Koo, D.E. Ioannou, J. Kopanski, J.S. Suehle and C.A. Richter. Silicon nanowire on oxide/nitride/oxide for memory application. Nanotechnology 18 (2007) 235204.
Michael E. Newman | EurekAlert!
New NASA study improves search for habitable worlds
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Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
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Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
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Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
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Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
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Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
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