Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Water Could Hold Answer to Graphene Nanoelectronics

Researchers at Rensselaer Polytechnic Institute developed a new method for using water to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics. In this optical micrograph image, a graphene film on a silicon dioxide substrate is being electrically tested using a four-point probe.
Researchers at Rensselaer Polytechnic Institute developed a new method for using water to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics. In this optical micrograph image, a graphene film on a silicon dioxide substrate is being electrically tested using a four-point probe.

Abstract:
Researchers at Rensselaer Polytechnic Institute Use Water to Open, Tune Graphene's Band Gap

Water Could Hold Answer to Graphene Nanoelectronics

Troy, NY | Posted on October 26th, 2010

Researchers at Rensselaer Polytechnic Institute developed a new method for using water to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics.

By exposing a graphene film to humidity, Rensselaer Professor Nikhil Koratkar and his research team were able to create a band gap in graphene — a critical prerequisite to creating graphene transistors. At the heart of modern electronics, transistors are devices that can be switched "on" or "off" to alter an electrical signal. Computer microprocessors are comprised of millions of transistors made from the semiconducting material silicon, for which the industry is actively seeking a successor.

Graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chain-link fence, has no band gap. Koratkar's team demonstrated how to open a band gap in graphene based on the amount of water they adsorbed to one side of the material, precisely tuning the band gap to any value from 0 to 0.2 electron volts. This effect was fully reversible and the band gap reduced back to zero under vacuum. The technique does not involve any complicated engineering or modification of the graphene, but requires an enclosure where humidity can be precisely controlled.

"Graphene is prized for its unique and attractive mechanical properties. But if you were to build a transistor using graphene, it simply wouldn't work as graphene acts like a semi-metal and has zero band gap," said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. "In this study, we demonstrated a relatively easy method for giving graphene a band gap. This could open the door to using graphene for a new generation of transistors, diodes, nanoelectronics, nanophotonics, and other applications."

Results of the study were detailed in the paper "Tunable Band gap in Graphene by the Controlled Adsorbtion of Water Molecules," published this week by the journal Small. See the full paper at: dx.doi.org/10.1002/smll.201001384

In its natural state, graphene has a peculiar structure but no band gap. It behaves as a metal and is known as a good conductor. This is compared to rubber or most plastics, which are insulators and do not conduct electricity. Insulators have a large band gap — an energy gap between the valence and conduction bands — which prevents electrons from conducting freely in the material.

Between the two are semiconductors, which can function as both a conductor and an insulator. Semiconductors have a narrow band gap, and application of an electric field can provoke electrons to jump across the gap. The ability to quickly switch between the two states — "on" and "off" — is why semiconductors are so valuable in microelectronics.

"At the heart of any semiconductor device is a material with a band gap," Koratkar said. "If you look at the chips and microprocessors in today's cell phones, mobile devices, and computers, each contains a multitude of transistors made from semiconductors with band gaps. Graphene is a zero band gap material, which limits its utility. So it is critical to develop methods to induce a band gap in graphene to make it a relevant semiconducting material."

The symmetry of graphene's lattice structure has been identified as a reason for the material's lack of band gap. Koratkar explored the idea of breaking this symmetry by binding molecules to only one side of the graphene. To do this, he fabricated graphene on a surface of silicon and silicon dioxide, and then exposed the graphene to an environmental chamber with controlled humidity. In the chamber, water molecules adsorbed to the exposed side of the graphene, but not on the side facing the silicon dioxide. With the symmetry broken, the band gap of graphene did, indeed, open up, Koratkar said. Also contributing to the effect is the moisture interacting with defects in the silicon dioxide substrate.

"Others have shown how to create a band gap in graphene by adsorbing different gasses to its surface, but this is the first time it has been done with water," he said. "The advantage of water adsorption, compared to gasses, is that it is inexpensive, nontoxic, and much easier to control in a chip application. For example, with advances in micro-packaging technologies it is relatively straightforward to construct a small enclosure around certain parts or the entirety of a computer chip in which it would be quite easy to control the level of humidity."

Based on the humidity level in the enclosure, chip makers could reversibly tune the band gap of graphene to any value from 0 to 0.2 electron volts, Korarkar said.

Along with Koratkar, authors on the paper are Theodorian Borca-Tasciuc, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer; Rensselaer mechanical engineering graduate student Fazel Yavari, who was first author on the paper; Rensselaer Focus Center New York Postdoctoral Research Associate Churamani Gaire; and undergraduate student Christo Kritzinger. Co-authors from Rice University are Professor Pulickel M. Ajayan; Postdoctoral Research Fellow Li Song; and graduate student Hemtej Gulapalli.

This study was supported by the Advanced Energy Consortium (AEC), National Institute of Standards and Technology (NIST) Nanoelectronics Research Initiative, and the U.S. Department of Energy Office of Basic Energy Sciences (BES).

For more information on Koratkar's graphene research at Rensselaer, visit:

Graphene Outperforms Carbon Nanotubes for Creating Stronger, More Crack-Resistant Materials news.rpi.edu/update.do?artcenterkey=2715

Rensselaer Researchers Secure $1 Million Grant To Develop Oil Exploration Game-Changer news.rpi.edu/update.do?artcenterkey=2700

Helping Hydrogen: Student Inventor Tackles Challenge of Hydrogen Storage
news.rpi.edu/update.do?artcenterkey=2690

Koratkar also was recently appointed as the editor of the journal Carbon: www.elsevier.com/wps/find/P10.cws_home/carbon_neweditors

####

For more information, please click here

Contacts:
Michael Mullaney
Phone: (518) 276-6161

Copyright © Rensselaer Polytechnic Institute

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

ANU invention to inspire new night-vision specs December 7th, 2016

Arrowhead Pharmaceuticals to Webcast Fiscal 2016 Year End Results December 7th, 2016

Journal Nanotechnology Progress International (JONPI), newest edition out December 7th, 2016

In IEDM 2016 Keynote, Leti CEO Says ‘Hyperconnectivity’, Human-focused Research and the IOT Promise Profound, Positive Changes December 7th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Physicists decipher electronic properties of materials in work that may change transistors December 6th, 2016

Construction of practical quantum computers radically simplified: Scientists invent ground-breaking new method that puts quantum computers within reach December 5th, 2016

Shape matters when light meets atom: Mapping the interaction of a single atom with a single photon may inform design of quantum devices December 4th, 2016

Research Study: MetaSOLTM Shatters Solar Panel Efficiency Forecasts with Innovative New Coating: Coating Provides 1.2 Percent Absolute Enhancement to Triple Junction Solar Cells December 2nd, 2016

Possible Futures

ANU invention to inspire new night-vision specs December 7th, 2016

In IEDM 2016 Keynote, Leti CEO Says ‘Hyperconnectivity’, Human-focused Research and the IOT Promise Profound, Positive Changes December 7th, 2016

Physicists decipher electronic properties of materials in work that may change transistors December 6th, 2016

Fast, efficient sperm tails inspire nanobiotechnology December 5th, 2016

Academic/Education

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

Enterprise In Space Partners with Sketchfab and 3D Hubs for NewSpace Education October 13th, 2016

New Agricultural Research Center Debuts at UCF October 12th, 2016

Chip Technology

Leti IEDM 2016 Paper Clarifies Correlation between Endurance, Window Margin and Retention in RRAM for First Time: Paper Presented at IEDM 2016 Offers Ways to Reconcile High-cycling Requirements and Instability at High Temperatures in Resistive RAM December 6th, 2016

Tokyo Institute of Technology research: 3D solutions to energy savings in silicon power transistors December 6th, 2016

Physicists decipher electronic properties of materials in work that may change transistors December 6th, 2016

Construction of practical quantum computers radically simplified: Scientists invent ground-breaking new method that puts quantum computers within reach December 5th, 2016

Nanotubes/Buckyballs/Fullerenes

Infrared instrumentation leader secures exclusive use of Vantablack coating December 5th, 2016

Novel Electrode Structure Provides New Promise for Lithium-Sulfur Batteries December 3rd, 2016

Cutting-edge nanotechnologies are breaking into industries November 18th, 2016

Hybrid nanostructures hold hydrogen well: Rice University scientists say boron nitride-graphene hybrid may be right for next-gen green cars October 25th, 2016

Nanoelectronics

Leti IEDM 2016 Paper Clarifies Correlation between Endurance, Window Margin and Retention in RRAM for First Time: Paper Presented at IEDM 2016 Offers Ways to Reconcile High-cycling Requirements and Instability at High Temperatures in Resistive RAM December 6th, 2016

Physicists decipher electronic properties of materials in work that may change transistors December 6th, 2016

Journal Nanotechnology Progress International (JONPI) Volume 6, issue 2 coming out soon! December 5th, 2016

Supersonic spray yields new nanomaterial for bendable, wearable electronics: Film of self-fused nanowires clear as glass, conducts like metal November 23rd, 2016

Announcements

ANU invention to inspire new night-vision specs December 7th, 2016

Arrowhead Pharmaceuticals to Webcast Fiscal 2016 Year End Results December 7th, 2016

Journal Nanotechnology Progress International (JONPI), newest edition out December 7th, 2016

In IEDM 2016 Keynote, Leti CEO Says ‘Hyperconnectivity’, Human-focused Research and the IOT Promise Profound, Positive Changes December 7th, 2016

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