Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Penn Researchers Take a Big Step Forward in Making Smaller Circuits

Abstract:
Nanotubes used to create a functional electronic circuit

Penn Researchers Take a Big Step Forward in Making Smaller Circuits

Philadelphia, PA | July 29, 2005

Physicists at the University of Pennsylvania have overcome a major hurdle in the race to create nanotube-based electronics. In an article in the August issue of the journal Nature Materials, available online now, the researchers describe their method of using nanotubes - tiny tubes entirely composed of carbon atoms - to create a functional electronic circuit. Their method creates circuits by dipping semiconductor chips into liquid suspensions of carbon nanotubes, rather than growing the nanotubes directly on the circuit.

"Given their amazing electric properties, nanotubes have been a subject of keen interest for creating such things as chemical sensors, flexible electronics and high-speed, high-device-density microprocessors for computing," said Alan T. Johnson, associate professor in Penn's Department of Physics and Astronomy. "The problem is that the properties we like best about nanotubes their size and physical properties also make them very difficult to manipulate."

Instead of growing nanotubes in a pattern on a silicon chip, as is conventionally done, the Penn researchers devised a means of "sprinkling" nanotubes onto chips.

University of Pennsylvania - An image showing a circuit made of nanotubes
An image showing a circuit made of nanotubes. Copyright © University of Pennsylvania
Click on image for larger version.

"We dip the chips into nanotubes much like dipping an ice cream cone into candy," said Danvers Johnston, a graduate student in Johnson's laboratory and lead author of the study. "Ultimately we can make it so that the nanotubes only stick where want them to in order to form a circuit."

Single-walled nanotubes are formed by turning a single sheet of carbon atoms into a seamless cylinder approximately one nanometer a billionth of a meter in diameter.

Nanotubes can be either semiconducting or "metallic" the latter is highly conductive to electricity depending on the exact geometry of the carbon atoms. Semiconducting nanotubes make for exceptional transistors, which is why so much attention has been devoted to finding a way to use them in electronics.

Previously, most nanotube circuits have been made by growing each nanotube on the surface of a chip, using a process known as chemical vapor deposition. Unfortunately, this method often results in a circuit comprised of both types of nanotubes, metallic and semiconducting. Furthermore, the growth direction of the nanotube is arbitrary, and their diameters are large. Small diameter carbon nanotubes are more useful for switches.

"Fortunately, other researchers have made it possible to grow small diameter nanotubes and to separate metallic from semiconducting nanotubes in solution," said Arjun Yodh, a professor in Penn's Department of Physics and Astronomy. "Ultimately our process can create a large batch of small diameter nanotubes in solution, can separate out the semiconducting nanotubes and then can place them in proper position on a patterned silicon chip."

The researchers, along with post-doctoral associate Mohammed F. Islam, found their biggest challenge in purifying the mass-produced nanotubes. The process they used to create nanotubes in bulk frequently adds impurities usually stray bits of carbon and leftover catalysts that ultimately detract from the quality of the nanotubes.

The Penn researchers found a purification scheme for the nanotubes by heating them in moist air with a gentle acid treatment and then using magnetic fields to separate the nanotubes from the impurities. They deposit the nanotubes by dipping a chip covered with a glue-like substance into the nanotube solution, and then they wash off the excess glue and whatever solvents that remain.

The resulting circuits take advantage of unique electrical properties of nanotubes and can be produced in bulk. Since the researchers can create nanotubes via processes separate from the chips, this process allows for a better control of the quality and diameter. The Penn researchers believe there is a definite role for nanotechnology in the future of electronics.

"The only way to make faster processors is to cram more transistors together," Johnson said. "Nanotubes are just about the smallest transistors that exist right now. So the more densely they can be packed on a chip, the faster the chips can become."

Funding for this research was provided by grants from the National Science Foundation and NASA.

####

Contact:
Greg Lester
215-898-8721
glester@pobox.upenn.edu

Copyright © University of Pennsylvania

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

Possible Futures

Fine felted nanotubes : Research team of Kiel University develops new composite material made of carbon nanotubes November 22nd, 2017

Report highlights opportunities and risks associated with synthetic biology and bioengineering November 22nd, 2017

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Chip Technology

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Nanometrics to Participate in the 6th Annual NYC Investor Summit 2017 November 16th, 2017

Nanotubes/Buckyballs/Fullerenes/Nanorods

NanoSummit in Luxembourg: single wall carbon nanotubes have entered our lives as we approach a nanoaugmented future November 23rd, 2017

Fine felted nanotubes : Research team of Kiel University develops new composite material made of carbon nanotubes November 22nd, 2017

TUBALL nanotube-based concentrates recognised as the most innovative raw material for composites by JEC Group November 7th, 2017

Nanotube fiber antennas as capable as copper: Rice University researchers show their flexible fibers work well but weigh much less October 23rd, 2017

Nanoelectronics

GLOBALFOUNDRIES, Fudan Team to Deliver Next Generation Dual Interface Smart Card November 14th, 2017

Leti Will Present 11 Papers and Host More-than-Moore Technologies Workshop November 14th, 2017

The next generation of power electronics? Gallium nitride doped with beryllium: How to cut down energy loss in power electronics? The right kind of doping November 9th, 2017

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

Announcements

NanoSummit in Luxembourg: single wall carbon nanotubes have entered our lives as we approach a nanoaugmented future November 23rd, 2017

JPK reports on the exciting research in the School of Medicine at Sungkyunkwan University (SKKU), Suwon, South Korea using the NanoWizard® ULTRA Speed AFM to understand the binding of transcription factor Sox2 with super enhancers November 23rd, 2017

Precision NanoSystems to host nanomedicines roundtable November 23rd, 2017

Fine felted nanotubes : Research team of Kiel University develops new composite material made of carbon nanotubes November 22nd, 2017

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