UC Irvine chemists create uniform conductive nanowires to be used in microelectronics

December 13, 2000

Practical construction method also allows for growth of long metal wires

UC Irvine chemists have developed a method for preparing metal nanowires featuring the conductivity, strength and length necessary for use in microelectronic devices, such as diodes and transistors, designed for emerging nanotechnologies.

Reginald Penner, UCI professor of chemistry--with graduate student researchers Michael P. Zach and Kwok Ng--built these new nanowires from molybdenum, an element used to strengthen steel. The wires were created using a method called step-edge decoration, which Penner said is proving to be an efficient way to construct these custom wires in large numbers. Results of the project will be published in the Dec. 15, 2000 issue of Science.

"Metal nanowires may be important to the future of nanotechnology, but there simply hasn't been a good general way to make them," Penner said. "Our new method for growing metal nanowires may prove to be an effective method for making the long, uniform conductive wires needed for connectors in future generations of nanometer-scale electronics."

In building these wires through the step-edge decoration process, the Penner group first electrochemically deposited molybdenum dioxide onto a piece of graphite. Rudimentary wires began growing when their molecules linked onto step edges--molecular defects on the graphite surface where the emerging wires could gain a stronger atomic hold. After the brittle molybdenum dioxide wires were formed, they were heated in hydrogen gas at 350 degrees to remove the oxygen, leaving only the molybdenum metal.

The resulting pure molybdenum wires were smaller in diameter but also stronger, more conductive and more flexible than those created in the first step of the process. The metal wires were then embedded in a polystyrene film and peeled off the graphite surface. The nanowires measured between 10 nanometers and a half-micron in diameter and up to 100 microns, or one-tenth of a millimeter, in length.

"By heating the molybdenum oxide in hydrogen, the wires we created were 1,000 times more conductive than the wires we electroplated in the first step of the process," Penner said. "For the practical applications that we foresee for these nanowires, the electronic conductivity is obviously extremely important."

In developing a method to build long, uniform nanowires, Penner said that the step-edge decoration method used on graphite is proving to be more practical than using template synthesis, which is another approach to building these wires used by researchers.

"The problem with templates is that you need a different one for every diameter of wire you want to grow," Penner said. "Also, thick templates needed to prepare long nanowires are not readily available. Our technique allows you to grow wires of any diameter you want as well as very long wires with a piece of graphite, which is something you can't do with existing templates."

Penner and his research team plan to continue their research by developing electronic devices with these nanowires, such as sensors, diodes and transistors.
-end-
The project was funded by the National Science Foundation Division of Materials Research, the American Chemical Society Petroleum Research Fund and the Camille and Henry Dreyfus Foundation.

A complete archive of press releases is available on the World Wide Web at www.communications.uci.edu

Note to editors: Images are available at www.communications.uci.edu/00releases/163tvfigindex.html

Contact:Tom Vasich
949-824-6455
tmvasich@uci.edu

University of California - Irvine

Related Nanowires Articles from Brightsurf:

A new, highly sensitive chemical sensor uses protein nanowires
Writing in NanoResearch, a team at UMass Amherst reports that they have developed bioelectronic ammonia gas sensors that are among the most sensitive ever made.

Giving nanowires a DNA-like twist
Argonne National Laboratory played a critical role in the discovery of a DNA-like twisted crystal structure created with a germanium sulfide nanowire, also known as a 'van der Waals material.' Researchers can tailor these nanowires in many different ways -- twist periods from two to twenty micrometers, lengths up to hundreds of micrometers, and radial dimensions from several hundred nanometers to about ten micrometers.

Shell increases versatility of nanowires
Nanowires promise to make LEDs more colorful and solar cells more efficient, in addition to speeding up computers.

Scientists synthesize new nanowires to improve high-speed communication
Scientists from the Institute of Process Engineering, City University of Hong Kong and their collaborators synthesized highly crystalline ternary In0.28Ga0.72Sb nanowires to demonstrate high carrier mobility and fast IR response.

Dose of vitamin C helps gold nanowires grow
Rice University scientists discover a method to turn stubby gold nanorods into gold nanowires of impressive length.

Silver nanowires promise more comfortable smart textiles
In a paper to be published in the forthcoming issue in NANO, researchers from the Nanjing University of Posts and Telecommunications have developed a simple, scalable and low-cost capillary-driven self-assembly method to prepare flexible and stretchable conductive fibers that have applications in wearable electronics and smart fabrics.

Artificial synapses made from nanowires
Scientists from J├╝lich together with colleagues from Aachen and Turin have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell.

Nanowires could make lithium ion batteries safer
From cell phones and laptops to electric vehicles, lithium-ion batteries are the power source that fuels everyday life.

Scientists have a new way to gauge the growth of nanowires
In a new study, researchers from the US Department of Energy's Argonne and Brookhaven National Laboratories observed the formation of two kinds of defects in individual nanowires, which are smaller in diameter than a human hair.

Cleaning nanowires to get out more light
A simple chemical surface treatment improves the performance of nanowire ultraviolet light-emitting diodes.

Read More: Nanowires News and Nanowires Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.