Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Electronics Play By a New Set of Rules at the Molecular Scale

Atomic scale visualization of the single molecule junctions formed with two equivalent pathways (left) and one pathway (right), including the bonding to the tips of two gold electrodes and a schematic of the external electrical circuit.
Atomic scale visualization of the single molecule junctions formed with two equivalent pathways (left) and one pathway (right), including the bonding to the tips of two gold electrodes and a schematic of the external electrical circuit.

Abstract:
In a paper published in Nature Nanontechnology on September 2, 2012, scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Columbia University's departments of Chemistry and of Applied Physics explore the laws that govern electronic conductance in molecular scale circuits.

Electronics Play By a New Set of Rules at the Molecular Scale

Upton, NY | Posted on September 2nd, 2012

"Everyone who has worked with basic electronic circuits knows that there are some simple rules of the road, like Ohm's Law," explains collaborator Mark Hybertsen, a physicist at Brookhaven's Center for Functional Nanomaterials (CFN). Hybertsen provided the theory to model the observed circuit behavior with the CFN's computational tools. "For several years we have been asking fundamental questions to probe how those rules might be different if the electronic circuit is shrunk down to the scale of a single molecule."

Conductance measures the degree to which a circuit conducts electricity. In a simple circuit, if you hook the resistors up in parallel, the electrons can flow through two different paths. In this case, the conductance of the full circuit will simply be the sum of the conductance of each resistor.

However, in a molecular circuit, the rules that govern current flow now involve fundamental quantum mechanics. In most single-molecule circuits, the molecules do not behave like conventional resistors; instead, the electrons tunnel through the molecule. When the molecule offers two pathways in parallel, the wave-like movement of an electron can dramatically change the way conductance adds up. For several years, experts in nanotechnology have suspected-but not proven-that quantum interference effects make the conductance of a circuit with two paths up to four times higher than the conductance of a circuit with a single path.

In order to investigate these quantum mechanical effects further, the scientists needed to construct their own controllable nano-size circuits. Working with Ronald Breslow's group at Columbia, they designed and synthesized a series of molecules to use in the experiment.

"Reliably making a circuit from a single molecule is really challenging," says Latha Venkataraman, a Columbia Engineering Applied Physics professor whose group perfected the method used to make the molecular circuits. "Imagine trying to touch the two ends of a molecule that is only ten atoms long."

To make the circuits, Venkataraman's group adapted a scanning tunneling microscope (STM) apparatus to repeatedly press a sharp gold tip into another gold electrode and then pull it away. When this junction breaks, there is a moment when the gap between the two pieces of gold is a perfect fit for the molecule. Once the circuit system is set up, the conductance measurement is fast and can be repeated thousands of times to get statistically reliable data.

Using this approach, the scientists discovered that the molecules with two built-in pathways like the one visualized in the figure at right had a conductance that was greater than the sum of each arm's conductance, although the increase was not as large as they had anticipated. In order to understand this effect better, Columbia's Hector Vasquez worked with Hybertsen to computationally simulate the quantum mechanical transmission of an electron through each circuit.

"Both the measurements and the simulations show that the molecules with two parallel paths can have a conductance that is bigger than two times that of molecule with a single path," said Hybertsen. "This is the signature that the quantum interference effect is playing a role."

The group suspects that other factors, such as the nature of the molecule's bond to the electrodes, need to be considered when calculating the conductance of a molecular circuit. They are currently looking into other central questions about molecular electronics, including how the device changes when different metals are used.

This research was funded primarily by the National Science Foundation and the New York State Office of Science, Technology, and Academic Research. Columbia's Rachid Skouta and Severin Schneebeli synthesized the experiment molecules with Ronald Breslow and Masha Kamanetska carried out the conductance measurements. The CFN at Brookhaven Lab is supported by the DOE's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

The Center for Functional Nanomaterials at Brookhaven National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit nano.energy.gov.

####

About Brookhaven National Laboratory
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more at www.bnl.gov/newsroom, follow Brookhaven Lab on Twitter, http://twitter.com/BrookhavenLab, or like us on Facebook, www.facebook.com/brookhavenlab .

For more information, please click here

Contacts:
Karen McNulty Walsh
(631) 344-8350

or
Peter Genzer
(631) 344-3174

Copyright © Brookhaven National Laboratory

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

Quantum twisted Loong confirms the physical reality of wavefunctions September 23rd, 2017

Application of air-sensitive semiconductors in nanoelectronics: 2-D semiconductor gallium selenide in encapsulated nanoelectronic devices September 22nd, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft robots' September 21st, 2017

Laboratories

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Ames Laboratory scientists move graphene closer to transistor applications August 30th, 2017

Imaging

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

Phenom-World selects Deben to supply a tensile stage as an accessory to their range of desktop SEMs August 29th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Quantum twisted Loong confirms the physical reality of wavefunctions September 23rd, 2017

DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft robots' September 21st, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

Chip Technology

Application of air-sensitive semiconductors in nanoelectronics: 2-D semiconductor gallium selenide in encapsulated nanoelectronic devices September 22nd, 2017

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

GLOBALFOUNDRIES Delivers 8SW RF SOI Technology for Next-Generation Mobile and 5G Applications: Advanced 8SW 300mm SOI technology enables cost-effective, high-performance RF front-end modules for 4G LTE mobile and sub-6GHz 5G applications September 20th, 2017

GLOBALFOUNDRIES Unveils Vision and Roadmap for Next-Generation 5G Applications: Technology platforms are uniquely positioned to enable a new era of ‘connected intelligence’ with the transition to 5G September 20th, 2017

Discoveries

Quantum twisted Loong confirms the physical reality of wavefunctions September 23rd, 2017

Application of air-sensitive semiconductors in nanoelectronics: 2-D semiconductor gallium selenide in encapsulated nanoelectronic devices September 22nd, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft robots' September 21st, 2017

Announcements

Quantum twisted Loong confirms the physical reality of wavefunctions September 23rd, 2017

Application of air-sensitive semiconductors in nanoelectronics: 2-D semiconductor gallium selenide in encapsulated nanoelectronic devices September 22nd, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft robots' September 21st, 2017

Tools

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

Phenom-World selects Deben to supply a tensile stage as an accessory to their range of desktop SEMs August 29th, 2017

New results reveal high tunability of 2-D material: Berkeley Lab-led team also provides most precise band gap measurement yet for hotly studied monolayer moly sulfide August 26th, 2017

Research partnerships

GLOBALFOUNDRIES Delivers Custom 14nm FinFET Technology for IBM Systems: Jointly developed 14HP process is world’s only technology that leverages both FinFET and SOI September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

A new approach to ultrafast light pulses: Unusual fluorescent materials could be used for rapid light-based communications systems September 19th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Quantum nanoscience

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

New quantum phenomena in graphene superlattices September 18th, 2017

Quantum detectives in the hunt for the world's first quantum computer September 8th, 2017

'Nano-hashtags' could provide definite proof of Majorana particles: Eindhoven network of nanowires gives particles the space to exchange places August 23rd, 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