Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Turning down the noise in graphene

New noise model shows all single layer graphene samples with an M-shaped pattern of noise (top) and all bi-layer graphene samples with a V-shaped noise pattern.
New noise model shows all single layer graphene samples with an M-shaped pattern of noise (top) and all bi-layer graphene samples with a V-shaped noise pattern.

Abstract:
Working with the unique nanoscience capabilities of the Molecular Foundry at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory, a multi-institutional team of researchers has developed the first model of signal-to-noise-ratios for low frequency noises in graphene on silica. Their results show noise patterns that run just the opposite of noise patterns in other electronic materials.

Turning down the noise in graphene

Berkeley, CA | Posted on August 7th, 2010

Graphene is a two-dimensional crystalline sheet of carbon atoms - meaning it is only one atom thick - through which electrons can race at nearly the speed of light - 100 times faster than they can move through silicon. This plus graphene's incredible flexibility and mechanical strength make the material a potential superstar for the electronics industry. However, whereas the best electronic materials feature a strong signal and weak background noise, attaining this high signal-to-noise ratio has been a challenge for both single and bi-layers of graphene, especially when placed on a substrate of silica or some other dielectric. One of the problems facing device developers has been the lack of a good graphene noise model.

Working with the unique nanoscience capabilities of the Molecular Foundry at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory, a multi-institutional team of researchers has developed the first model of signal-to-noise-ratios for low frequency noises in graphene on silica. Their results show noise patterns that run just the opposite of noise patterns in other electronic materials.

Berkeley Lab materials scientist Yuegang Zhang led a study in which it was determined that for graphene on silica, the background signal noise is minimal near the region in the graphene where the electron density of states (the number of energy states available to each electron) is lowest. For semiconductors, such as silicon, in the region where electron density states is low the background noise is at its highest. However, there were distinct differences in the noise patterns of single and bi-layer graphene.

"In this work, we present the four-probe low frequency noise characteristics in single- and bi-layer graphene samples, using a back-gated device structure that helps simplify the physics in understanding the interactions between the graphene and the silica substrate," says Zhang. "For single-layer graphene we found that the noise was reduced either close to or far away from the lowest electron density of states, sometimes referred to as the Dirac point for graphene, forming an M-shaped pattern. For the bi-layer graphene, we found a similar noise reduction near the Dirac point but an increase away from that point, forming a V-shaped pattern. The noise data near the Dirac point correlated to spatial-charge inhomogeneity."

The results of this research are reported in the journal Nano Letters in a paper titled "Effect of Spatial Charge Inhomogeneity on 1/f Noise Behavior in Graphene." Co-authoring the paper with Zhang were Guangyu Xu, Carlos Torres Jr., Fei Liu, Emil Song, Minsheng Wang, Yi Zhou, Caifu Zeng and Kang Wang.

Lead author Guangyu Xu, a physicist with the Department of Electrical Engineering at the University of California (UC) Los Angeles, says the spatial charge inhomogeneity responsible for the graphene's unique noise patterns was probably caused by the charge impurities near the graphene-substrate interface.

"Our experiment carefully rules out other possible extrinsic factors that might influence the result," Xu says. "We conclude the correlation between the anomalous noise feature and the spatial charge inhomogeneity, is one of the main carrier scattering mechanisms for unsuspended graphene samples."

Xu says this model of low frequency noise characteristics in graphene should be a significant help for fabricating electronic devices because biasing at the low noise regime can be designed into the device.

"This will benefit the high signal-to-noise ratio in graphene," Xu says.

This work was supported in part by DOE's Office of Science.

The Molecular Foundry is one of the five DOE Nanoscale Science Research Centers (NSRCs), national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The other NSRCs are located at DOE's Argonne, Brookhaven, Oak Ridge and Sandia and Los Alamos National Laboratories.

####

About Berkeley Lab
Berkeley Lab is a U.S. Department of Energy (DOE) national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California for the DOE Office of Science.

For more information, please click here

Contacts:
Lynn Yarris
(510) 486-5375

Copyright © Berkeley Lab

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Caught on camera -- chemical reactions 'filmed' at the single-molecule level March 22nd, 2017

Rare-earths become water-repellent only as they age March 22nd, 2017

Pulverizing e-waste is green, clean -- and cold: Rice, Indian Institute researchers use cryo-mill to turn circuit boards into separated powders March 21st, 2017

CRMGroup in Belgium uses a Deben three point bending stage in the development of new steel & coated steel products for automotive and other industrial applications March 21st, 2017

Govt.-Legislation/Regulation/Funding/Policy

Electro-optical switch transmits data at record-low temperatures: Operating at temperatures near absolute zero, switch could enable significantly faster data processing with lower power consumption March 20th, 2017

AIM Photonics Welcomes Coventor as Newest Member: US-Backed Initiative Taps Process Modeling Specialist to Enable Manufacturing of High-Yield, High-Performance Integrated Photonic Designs March 16th, 2017

Researchers develop groundbreaking process for creating ultra-selective separation membranes: Discovery could greatly improve energy-efficiency of separation and purification processes in the chemical and petrochemical industries March 15th, 2017

Nanogate Expands Sustainability Management: Nanogate publishes a statement of compliance with the German Sustainability Code for the first time March 15th, 2017

Academic/Education

AIM Photonics Welcomes Coventor as Newest Member: US-Backed Initiative Taps Process Modeling Specialist to Enable Manufacturing of High-Yield, High-Performance Integrated Photonic Designs March 16th, 2017

Nominations Invited for $250,000 Kabiller Prize in Nanoscience: Major international prize recognizes a visionary nanotechnology researcher February 20th, 2017

Oxford Nanoimaging report on how the Nanoimager, a desktop microscope delivering single molecule, super-resolution performance, is being applied at the MRC Centre for Molecular Bacteriology & Infection November 22nd, 2016

The University of Applied Sciences in Upper Austria uses Deben tensile stages as an integral part of their computed tomography research and testing facility October 18th, 2016

Nanotubes/Buckyballs/Fullerenes

Intertronics introduce new nanoparticle deagglomeration technology March 15th, 2017

Boron atoms stretch out, gain new powers: Rice University simulations demonstrate 1-D material's stiffness, electrical versatility January 26th, 2017

New stem cell technique shows promise for bone repair January 25th, 2017

Captured on video: DNA nanotubes build a bridge between 2 molecular posts: Research may lead to new lines of direct communication with cells January 9th, 2017

Announcements

Caught on camera -- chemical reactions 'filmed' at the single-molecule level March 22nd, 2017

Rare-earths become water-repellent only as they age March 22nd, 2017

Pulverizing e-waste is green, clean -- and cold: Rice, Indian Institute researchers use cryo-mill to turn circuit boards into separated powders March 21st, 2017

CRMGroup in Belgium uses a Deben three point bending stage in the development of new steel & coated steel products for automotive and other industrial applications March 21st, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project