Featured Research

from universities, journals, and other organizations

Water clears path for nanoribbon development

Date:
July 30, 2013
Source:
Rice University
Summary:
A tiny meniscus of water makes it practical to form long graphene nanoribbons less than 10 nanometers wide.

New research at Rice University shows how water makes it practical to form long graphene nanoribbons less than 10 nanometers wide.

And it's unlikely that many of the other labs currently trying to harness the potential of graphene, a single-atom sheet of carbon, for microelectronics would have come up with the technique the Rice researchers found while they were looking for something else.

The discovery by lead author Vera Abramova and co-author Alexander Slesarev, both graduate students in the lab of Rice chemist James Tour, appears online this month in the American Chemical Society journal ACS Nano.

A bit of water adsorbed from the atmosphere was found to act as a mask in a process that begins with the creation of patterns via lithography and ends with very long, very thin graphene nanoribbons. The ribbons form wherever water gathers at the wedge between the raised pattern and the graphene surface.

The water formation is called a meniscus; it is created when the surface tension of a liquid causes it to curve. In the Rice process, the meniscus mask protects a tiny ribbon of graphene from being etched away when the pattern is removed.

Tour said any method to form long wires only a few nanometers wide should catch the interest of microelectronics manufacturers as they approach the limits of their ability to miniaturize circuitry. "They can never take advantage of the smallest nanoscale devices if they can't address them with a nanoscale wire," he said. "Right now, manufacturers can make small features, or make big features and put them where they want them. But to have both has been difficult. To be able to pattern a line this thin right where you want it is a big deal because it permits you to take advantage of the smallness in size of nanoscale devices."

Tour said water's tendency to adhere to surfaces is often annoying, but in this case it's essential to the process. "There are big machines that are used in electronics research that are often heated to hundreds of degrees under ultrahigh vacuum to drive off all the water that adheres to the inside surfaces," he said. "Otherwise there's always going to be a layer of water. In our experiments, water accumulates at the edge of the structure and protects the graphene from the reactive ion etching (RIE). So in our case, that residual water is the key to success.

"Nobody's ever thought of this before, and it's nothing we thought of," Tour said. "This was fortuitous."

Abramova and Slesarev had set out to fabricate nanoribbons by inverting a method developed by another Rice lab to make narrow gaps in materials. The original method utilized the ability of some metals to form a native oxide layer that expands and shields material just on the edge of the metal mask. The new method worked, but not as expected.

"We first suspected there was some kind of shadowing," Abramova said. But other metals that didn't expand as much, if at all, showed no difference, nor did varying the depth of the pattern. "I was basically looking for anything that would change something."

It took two years to develop and test the meniscus theory, during which the researchers also confirmed its potential to create sub-10-nanometer wires from other kinds of materials, including platinum. They also constructed field-effect transistors to check the electronic properties of graphene nanoribbons.

To be sure that water does indeed account for the ribbons, they tried eliminating its effect by first drying the patterns by heating them under vacuum, and then by displacing the water with acetone to eliminate the meniscus. In both cases, no graphene nanoribbons were created.

The researchers are working to better control the nanoribbons' width, and they hope to refine the nanoribbons' edges, which help dictate their electronic properties.

"With this study, we figured out you don't need expensive tools to get these narrow features," Tour said. "You can use the standard tools a fab line already has to make features that are smaller than 10 nanometers."

The Air Force Office of Scientific Research and the Office of Naval Research Multidisciplinary University Research Initiative Graphene Program supported the research.


Story Source:

The above story is based on materials provided by Rice University. The original article was written by Mike Williams. Note: Materials may be edited for content and length.


Journal Reference:

  1. Vera Abramova, Alexander S. Slesarev, James M. Tour. Meniscus-Mask Lithography for Narrow Graphene Nanoribbons. ACS Nano, 2013; 130726154515004 DOI: 10.1021/nn403057t

Cite This Page:

Rice University. "Water clears path for nanoribbon development." ScienceDaily. ScienceDaily, 30 July 2013. <www.sciencedaily.com/releases/2013/07/130730123251.htm>.
Rice University. (2013, July 30). Water clears path for nanoribbon development. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2013/07/130730123251.htm
Rice University. "Water clears path for nanoribbon development." ScienceDaily. www.sciencedaily.com/releases/2013/07/130730123251.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Stranded Whale Watching Boat Returns to Boston

Stranded Whale Watching Boat Returns to Boston

Reuters - US Online Video (July 29, 2014) Passengers stuck overnight on a whale watching boat return safely to Boston. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins