IBM researchers today announced a discovery that combats one of the industry's most perplexing problems in using graphite -- the same material found inside pencils -- as a material for building nanoelectonic circuits vastly smaller than those found in today's silicon based computer chips.
For the first time anywhere, IBM scientists have found a way to suppress unwanted interference of electrical signals created when shrinking graphene, a two-dimensional, single-atomic layer thick form of graphite, to dimensions just a few atoms long.
Scientists around the world are exploring the use of graphene as a much smaller replacement for today's silicon transistors. Graphene is a two-dimensional honeycomb lattice of carbon atoms, similar to atomic-scale chicken-wire, which has attracted strong scientific and technological interest because it exhibits promising electrical properties and could be used in transistors and circuits at scales vastly smaller than components inside of today's tiniest computer chips.
One problem in using these nano-devices is the inverse relationship between the size of the device and the amount of uncontrolled electrical noise that is generated: as they are made smaller and smaller, the noise -- electrical charges that bounce around the material causing all sorts of interference that impede their usefulness -- grows larger and larger. This trend is known as Hooge's rule, and occurs in traditional silicon based devices as well as in graphene nano-ribbons and carbon nanotube based devices.
"The effect of noise from Hooge's rule is exaggerated at the nanoscale because the dimensions are approaching the nearly smallest limits, down to only a handful of atoms, and the noise that is created can overwhelm the electrical signal that needs to be achieved to be useful," said IBM Researcher Dr. Phaedon Avouris, who leads IBM's exploration into carbon nanotubes and graphene. "To quote the famous physicist Rolf Landauer, at the nanoscale 'the noise is your signal'; in other words, you cannot produce any useful electronic device at the nanoscale if the noise is comparable to the signal you are trying to switch on and off."
Now, IBM scientists have found that the noise in graphene-based semiconductor devices can, in fact, be suppressed and report the results today in the journal Nano Letters.
In their experiments, the IBM Researchers first used a single layer, or sheet, of graphene to build a transistor and noted that the device does in fact follow Hooge's Rule: as they are made smaller and smaller, there is an increase in the noise that is created.
Two Layers Are Better Than One
However, when the IBM Researchers built the same device with two sheets of graphene instead of one -- one stacked on top of the other -- they noted that the noise is suppressed, and is weak enough that these so-called bilayer graphene ribbons could prove useful for building future semiconductor devices for use in sensors, communications devices, computing systems and more. The noise is inhibited because of the strong electronic coupling between the two graphene layers that counteracts the influence of the noise sources: the system acts as a noise insulator.
While further detailed analysis and studies are required to better understand these phenomena, the findings provide exciting opportunities for graphene bilayers in a variety of applications.
The report on this work, entitled "Strong Suppression of Electrical Noise in Bilayer Graphene Nanoribbons" by Yu-Ming Lin and Phaedon Avouris of IBM's T.J.Watson Research Center in Yorktown Heights, N.Y. is available online at the journal
Nano Letters:
http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/asap/abs/nl080241l.html
Source: IBM
Related stories:
An oblivious transfer protocol for quantum cryptography
“It's hard to beat the noise that you have with quantum information,” Barbara Terhal tells PhysOrg.com. “So our security protocol relies on the fact that storing quantum bits noiselessly is hard to do with current technology.”
Hitachi Achieves Nanotechnology Milestone for Quadrupling Terabyte Hard Drive
Hitachi, Ltd. announced today they have developed the world’s smallest read-head technology for hard disk drives, which is expected to quadruple current storage capacity limits to four terabytes (TB) on a desktop hard drive and one TB on a notebook hard drive.
Using video-game technology to find oil, gas
What do video games and seismic explorations have in common? Both require very demanding computer applications that call for the ability to process massive quantities of data rapidly. Using computer technology originally co-designed by IBM for video-game consoles, University of Houston seismic researchers are employing this extremely fast technology to more effectively target oil reserves.
Discovering How to Focus on Tiniest of the Very Small
If you need a good picture of a molecule, your first job is getting its atoms to pose for you, says John Silcox, Cornell's David E. Burr Professor of Engineering and an expert in the realm of the very tiny.
Researchers recover typed text using audio recording of keystrokes
A new security threat revealed by computer scientists at the University of California, Berkeley, may be enough to drive some people away from their computer keyboards and back to pen and paper. The researchers show that a simple audio recording of those keyboard clicks can betray the text you just entered, from passwords to secret love notes.
Power lines may offer Internet connections
There are three basic on-ramps to the broadband highway: cable telephone line or satellite -- but electric companies may soon join the fray.
IBM Announces New CMOS Image Sensor Foundry Offering
IBM today announced the availability of technology and manufacturing services for complementary metal oxide semiconductor (CMOS) image sensors for use in camera-phones, digital still cameras and other consumer products. The offering combines IBM's copper process technology with image sensor intellectual property licensed from Eastman Kodak Company to produce CMOS image sensors that can offer industry-leading image quality for high-volume consumer applications.
Magma's QuickCap NX Sets New Standard in Parasitic Capacitance Extraction for 90nm Designs
Magma Design Automation Inc., a provider of chip design solutions, today announced QuickCap NX, an enhanced version of its gold-standard QuickCap parasitic capacitance extraction tool. The key capabilities that have been added allow the tool to better address design challenges that occur in 90-
nanometer (nm) and smaller process technologies. With advanced new process modeling, technology model encryption, a parallel execution mode, reference-level SPICE netlist generation and a new 3D graphics viewer, users can shorten the design cycle by more accurately predicting silicon performance.
