Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



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

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Govt.-Legislation/Regulation/Funding/Policy

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Academic/Education

Rice University launches Rice Synthetic Biology Institute to improve lives January 12th, 2024

Multi-institution, $4.6 million NSF grant to fund nanotechnology training September 9th, 2022

National Space Society Helps Fund Expanding Frontier’s Brownsville Summer Entrepreneur Academy: National Space Society and Club for the Future to Support Youth Development Program in South Texas June 24th, 2022

How a physicist aims to reduce the noise in quantum computing: NAU assistant professor Ryan Behunin received an NSF CAREER grant to study how to reduce the noise produced in the process of quantum computing, which will make it better and more practical April 1st, 2022

Nanotubes/Buckyballs/Fullerenes/Nanorods/Nanostrings

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

TU Delft researchers discover new ultra strong material for microchip sensors: A material that doesn't just rival the strength of diamonds and graphene, but boasts a yield strength 10 times greater than Kevlar, renowned for its use in bulletproof vests November 3rd, 2023

Tests find no free-standing nanotubes released from tire tread wear September 8th, 2023

Detection of bacteria and viruses with fluorescent nanotubes July 21st, 2023

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project