Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Adding Hydrogen Triples Transistor Performance in Graphene

Joshua Robinson

Optical image of transistors and structures to test device performance on hydrogenated epitaxial graphene
Joshua Robinson

Optical image of transistors and structures to test device performance on hydrogenated epitaxial graphene

Abstract:
A technique that uses hydrogen to improve transistor performance on real-world graphene devices has been demonstrated on the wafer-scale by researchers in Penn State's Electro-Optics Center (EOC). In a paper published in the August 1, 2011, online edition of Nano Letters, the researchers demonstrated a 3x improvement in electron mobility of epitaxial graphene grown on the silicon face of a 100 mm silicon carbide wafer, as well as a similar improvement in radio-frequency transistor performance.

Adding Hydrogen Triples Transistor Performance in Graphene

University Park, PA | Posted on August 31st, 2011

"There are two faces to a silicon carbide wafer," explains EOC materials scientist Joshua Robinson. "Graphene grown on the carbon face usually has higher electron mobility, but that's because beneath the graphene layer grown on the silicon face there is a carbon-rich buffer layer bound to the silicon carbide that acts to scatter electrons, thus reducing their mobility. If you can get rid of the buffer layer, the electrons will go much faster, which means your devices will work faster. It is also easier to control the thickness of the graphene on the silicon face, which is crucial if you want to make highly uniform wafer-scale devices. That's what we've been able to do."

The paper, titled "Epitaxial Graphene Transistors: Enhancing Performance via Hydrogen Intercalation," reports an extrinsic cut-off frequency of 24 GHz in transistor performance, the highest reported so far in a real-world epitaxial graphene device, the authors believe. (Extrinsic cut-off frequency is a measure of device speed under operating conditions, and is typically a fraction of intrinsic speeds often reported.) The hydrogenation technique, which was first developed by a group in Germany (Riedl, et al.; Phys. Rev. Lett. 2009, 103, 246804), involves turning the buffer layer into a second, free-floating one-atom-thick layer of graphene by passivating dangling carbon bonds using hydrogen. This results in two free-floating layers of graphene. Penn State researchers, led by Joshua Robinson and David Snyder, have implemented an additional process step to their wafer-scale graphene synthesis process that fully converts the buffer layer to graphene. With this hydrogenation technique, the epitaxial graphene test structures showed a 200-300% increase in carrier mobility, from 700-900 cm2/(V s) to an average of 2050 cm2/(V s) in air and 2375 cm2/(V s) in vacuum.

The Penn State team, which includes lead author Robinson, David Snyder, Matthew Hollander, Michael LaBella, III, Kathleen A. Trumbull and Randy Cavalero, intend to use this technique to improve transistor performance in radio frequency devices. "Graphene's ambipolar conduction allows you to simplify circuits, while its high mobility and electron velocity provides a means to get to terahertz operation. The problem is that the exemplary frequency response reported to-date in the literature is not the real-world performance.

Hydrogenation and device scaling gets us much closer to true high frequency performance," Robinson remarks.

In a second paper in the same issue of Nano Letters, the group also reports a novel oxide seeding technique by atomic layer deposition they developed to deposit dielectric materials on wafer-scale epitaxial graphene. Their technique resulted in a 2-3x performance boost over more traditional seeding methods. The authors believe that these two advances constitute the next building blocks in creating viable graphene based technologies for use in radio frequency applications. The second paper, "Enhanced Transport and Transistor Performance with Oxide Seeded High-k Gate Dielectrics on Wafer-Scale Epitaxial Graphene," was coauthored by Matthew J. Hollander, Michael LaBella, Zachary R. Hughes, Michael Zhu, Kathleen A. Trumbull, Randal Cavalero, David W. Snyder, Xiaojun Wang, Euichul Hwang, Suman Datta, and Joshua A. Robinson, all of Penn State.

Their work on graphene based radio frequency transistors is supported by the Naval Surface Warfare Center, Crane, Indiana. Device fabrication was carried out at the Penn State Materials Research Institute Nanofabrication Facility, with support from the National Nanotechnology Infrastructure Network (NNIN).

####

About Penn State Materials Research Institute
The Materials Research Institute coordinates Penn State’s interdisciplinary materials-related research activities, encompassing more than 200 faculty groups. Penn State’s signature scientific research building, the Millennium Science Complex, is scheduled to open in Fall 2011. Housing both the Materials Research Institute and the Huck Institutes for the Life Sciences, this building is designed to integrate the physical and life sciences and engineering.

For more information, please click here

Contacts:
Joshua A. Robinson, Ph.D.

Copyright © Newswise

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

Pixelligent Launches New PixClear® Light Extraction Materials for OLED Lighting August 4th, 2015

The annual meeting on High Power Diode Lasers & Systems will be held as part of the Enlighten Conference, October 14th & 15th August 4th, 2015

Atomic view of microtubules: Berkeley Lab researchers achieve record 3.5 angstroms resolution and visualize action of a major microtubule-regulating protein August 4th, 2015

World's quietest gas lets physicists hear faint quantum effects August 4th, 2015

Graphene

Better together: Graphene-nanotube hybrid switches August 3rd, 2015

This could replace your silicon computer chips: A new semiconductor material made from black phosphorus may be a candidate to replace silicon in future tech July 30th, 2015

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Stretching the limits on conducting wires July 25th, 2015

Chip Technology

Small tilt in magnets makes them viable memory chips August 3rd, 2015

Better together: Graphene-nanotube hybrid switches August 3rd, 2015

MIPT researchers clear the way for fast plasmonic chips August 3rd, 2015

Thin films offer promise for ferroelectric devices: Researchers at Tokyo Institute of Technology demystify the ferroelectric properties observed in hafnium-oxide-based thin films, revealing a potentially useful device material August 3rd, 2015

Discoveries

Atomic view of microtubules: Berkeley Lab researchers achieve record 3.5 angstroms resolution and visualize action of a major microtubule-regulating protein August 4th, 2015

World's quietest gas lets physicists hear faint quantum effects August 4th, 2015

Artificial blood vessels become resistant to thrombosis August 4th, 2015

Engineering a better 'Do: Purdue researchers are learning how August 4th, 2015

Announcements

Artificial blood vessels become resistant to thrombosis August 4th, 2015

Engineering a better 'Do: Purdue researchers are learning how August 4th, 2015

Proving nanoparticles in sunscreen products August 4th, 2015

Global Carbon Nanotubes Industry 2015: Acute Market Reports August 4th, 2015

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