Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rice researchers make ultrasensitive conductivity measurements

11.06.2015

Photonic platform could provide 'optical signatures' for molecular electronics

Researchers at Rice University have discovered a new way to make ultrasensitive conductivity measurements at optical frequencies on high-speed nanoscale electronic components.


The animation shows how a "charge transfer plasmon" oscillates between linked nano disks.

Credit: Yue Zhang/Rice University

The research at Rice's Laboratory for Nanophotonics (LANP) is described online in a new study in the American Chemical Society's journal ACS Nano. In a series of experiments, LANP researchers linked pairs of puck-shaped metal nanodisks with metallic nanowires and showed how the flow of current at optical frequencies through the nanowires produced "charge transfer plasmons" with unique optical signatures.

"The push to continually increase the speed of microchip components has researchers looking at nanoscale devices and components that operate at optical frequencies for next-generation electronics," said LANP Director Naomi Halas, the lead scientist on the study. "It is not well-known how these materials and components operate at extremely high frequencies of light, and LANP's new technique provides a way to measure the electrical transport properties of nanomaterials and structures at these extremely high frequencies."

Halas is Rice's Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering. Her lab specializes in the study of nanoparticles that interact with light. For example, some metallic nanoparticles convert light into plasmons, waves of electrons that flow like a fluid across the particle's surface. In dozens of studies over the past two decades, LANP researchers have explored the basic physics of plasmonics and shown how plasmonic interactions can be harnessed for applications as diverse as medical diagnostics, cancer treatment, solar-energy collection and optical computing.

One type of plasmonic interaction that Halas' team has long studied is plasmonic coupling, a kind of interacting dance that plasmons engage in when two or more plasmonic particles are located near one another. For instance, when two puck-shaped plasmonic nanodisks are located near one another, they act like a tiny, light-activated capacitor. When a conducting wire is used to bridge the two, their plasmon energies change and a new resonance called a "charge transfer" plasmon, appears at a distinct frequency.

In the new research, study lead author Fangfang Wen, a Rice graduate student at LANP, examined the optical properties of pairs of bridged nanodisks . When she created plasmons in the pairs, she observed the charge flowing back and forth along the wires at optical frequencies. In examining the charge transfer plasmons in these pairs, she discovered that the electrical current flowing across the junction introduced a characteristic optical signature.

"In the case where a conducting wire was present in the junction, we saw an optical signature that was very different from the case without a wire," Wen said. Wen then set up a series of experiments where she varied the width and shape of the bridging nanowires and repeated these measurements for nanowires of two different metals, gold and aluminum.

These experiments revealed two key findings. First, at the low end of the conductance scale, she found that even the slightest changes in conductivity resulted in notable optical shifts -- a finding that could be particularly interesting for molecular-electronics researchers who are interested in measuring conductivity in structures as small as a single molecule.

"We also found that our platform gave a different optical signature in cases where the level of conductance was the same but the junction material was different," Wen said. "If we had nanowires with the same conductance that were made of different materials, we saw a different optical signature. If we used the same material, with different geometries, we saw the same signature."

This specificity and repeatability could also be useful to researchers who might want to use this approach to identify the conductance of nanowires, or other nanoscale electronic components, at optical frequencies. "The optical frequency conductance of most materials is not known," she said. "This provides a useful and practical method to measure this property.

"To reduce the size of electronics even beyond today's limits, scientists want to study electron transfer through a single molecule, particularly at extremely high, even optical frequencies," Wen said. "Such changes cannot be measured using standard electronic devices or instruments that operate at microwave frequencies. Our research provides a new platform for the measurement of nanoscale conductance at optical frequencies."

In recognition of the research's potential to improve "people's lives through the transforming power of chemistry," the American Chemical Society made the paper an ACS Editors' Choice and is making it freely available for public access online.

###

Study co-authors include Peter Nordlander, the Wiess Chair and Professor of Physics and Astronomy at Rice, and Rice graduate students Yue Zhang, Samuel Gottheim, Nicholas King and Yu Zhang. The research was supported by the Robert A. Welch Foundation, the Department of Defense's National Security Science and Engineering Faculty Fellowship Program, the Defense Threat Reduction Agency, the Air Force Office of Scientific Research and the Army.

A copy of the ACS Nano paper is available at: http://pubs.acs.org/doi/abs/10.1021/acsnano.5b02087

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations on Twitter @RiceUNews.

Media Contact

David Ruth
david@rice.edu
713-348-6327

 @RiceUNews

http://news.rice.edu 

David Ruth | EurekAlert!

More articles from Information Technology:

nachricht Robots as Tools and Partners in Rehabilitation
17.08.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Low bandwidth? Use more colors at once
17.08.2018 | Purdue University

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>