|
Northwestern researchers develop bistable nanoswitch
October 16, 2006EVANSTON, Ill. - Carbon nanotubes (CNT) have been under intense study by scientists all over the world for more than a decade and are being thought of as ideal building blocks for nanoelectromechanical systems (NEMS). A type of one-dimensional structure with high-aspect ratio, carbon nanotubes have emerged as a promising material because of their many impressive mechanical, electrical and chemical properties.
Now scientists from Northwestern University have demonstrated a novel carbon nanotube-based nanoelectromechanical switch exhibiting bistability based on current tunneling. The device could help advance technological developments in memory chips and electronic sensing devices.
The research is published online by the scientific journal Small.
"We believe the unique characteristics of this nano device will likely lead to many high-impact applications in the field of nanoelectronics and nanosensors," said Horacio Espinosa, professor of mechanical engineering in the McCormick School of Engineering and Applied Science. Espinosa and Changhong Ke, a former graduate student of Espinosa's, co-authored the paper.
Since the invention of the integrated circuit (IC), the semiconductor industry has boomed following the famous Moore's law. However, as the characteristic dimension achievable by various photolithography techniques approaches its physical limits, scientists are searching for new materials and new device concepts to be able to continue the large-scale integration trend.
"Although several carbon nanotube-based NEMS devices have been proposed, frankly, none of them has reached the level of commercial success," said Espinosa. "There are many challenges associated with nanofabrication and reliability."
Nanoscale manufacturing is complex and too expensive, imposing significant challenges to the design of nano devices. Assessing device reliability based on nanoscale experimentation is one big challenge. For example, placement of nano-objects at desired locations is difficult and lacks reproducibility. Likewise, real-time observation and characterization of mechanical motion requires the use of in-situ electron microscopy and electronic measurement techniques capable of controlling noise and parasitic effects.
Espinosa and his team solved some of these issues by designing and demonstrating a tunneling bistable switch. The device is made of a free suspended multiwalled carbon nanotube interacting electrostatically with an underlying electrode. In the device circuit, there is a resistor in series with the nanotube, which plays an important role in the functioning of the device by adjusting the voltage drop between the nanotube and the underlying electrode.
"The design of the device looks very simple, but the theories behind it are very complex and span several disciplines, including quantum mechanics, electronics and mechanics," said co-inventor Ke, now a post-doctoral fellow at Duke University. "Also, a major advantage of our device is its geometry, which is fully compatible with current manufacturing techniques for mass production."
Espinosa and Ke demonstrated the behaviors of the device by mounting individual carbon nanotubes to the tip of a tungsten probe using a nanomanipualtor inside a scanning electron microscope. Then the nanotube was actuated by applying a potential to an adjustable micron-size gap between the nanotube and an electrode. The motion of the nanotube was recorded by the electron microscope, and the current in the circuit was recorded by a source-measurement unit.
Northwestern has filed a patent application covering the concept of the bistable tunneling device and its application and is seeking commercial partners to develop the technology. The potential applications of the device include NEMS switches, random-access memory elements and logic devices.
Northwestern University
"We believe the unique characteristics of this nano device will likely lead to many high-impact applications in the field of nanoelectronics and nanosensors," said Horacio Espinosa, professor of mechanical engineering in the McCormick School of Engineering and Applied Science. Espinosa and Changhong Ke, a former graduate student of Espinosa's, co-authored the paper.
Since the invention of the integrated circuit (IC), the semiconductor industry has boomed following the famous Moore's law. However, as the characteristic dimension achievable by various photolithography techniques approaches its physical limits, scientists are searching for new materials and new device concepts to be able to continue the large-scale integration trend.
"Although several carbon nanotube-based NEMS devices have been proposed, frankly, none of them has reached the level of commercial success," said Espinosa. "There are many challenges associated with nanofabrication and reliability."
Nanoscale manufacturing is complex and too expensive, imposing significant challenges to the design of nano devices. Assessing device reliability based on nanoscale experimentation is one big challenge. For example, placement of nano-objects at desired locations is difficult and lacks reproducibility. Likewise, real-time observation and characterization of mechanical motion requires the use of in-situ electron microscopy and electronic measurement techniques capable of controlling noise and parasitic effects.
Espinosa and his team solved some of these issues by designing and demonstrating a tunneling bistable switch. The device is made of a free suspended multiwalled carbon nanotube interacting electrostatically with an underlying electrode. In the device circuit, there is a resistor in series with the nanotube, which plays an important role in the functioning of the device by adjusting the voltage drop between the nanotube and the underlying electrode.
"The design of the device looks very simple, but the theories behind it are very complex and span several disciplines, including quantum mechanics, electronics and mechanics," said co-inventor Ke, now a post-doctoral fellow at Duke University. "Also, a major advantage of our device is its geometry, which is fully compatible with current manufacturing techniques for mass production."
Espinosa and Ke demonstrated the behaviors of the device by mounting individual carbon nanotubes to the tip of a tungsten probe using a nanomanipualtor inside a scanning electron microscope. Then the nanotube was actuated by applying a potential to an adjustable micron-size gap between the nanotube and an electrode. The motion of the nanotube was recorded by the electron microscope, and the current in the circuit was recorded by a source-measurement unit.
Northwestern has filed a patent application covering the concept of the bistable tunneling device and its application and is seeking commercial partners to develop the technology. The potential applications of the device include NEMS switches, random-access memory elements and logic devices.
Northwestern University
Carbon Nanotube News and Current Carbon Nanotube Events RSSResearchers create the first thermal nanomotor in the world
Researchers from the UAB Research Park have created the first nanomotor that is propelled by changes in temperature. A carbon nanotube is capable of transporting cargo and rotating like a conventional motor, but is a million times smaller than the head of a needle.
Carbon nanotubes made into conductive, flexible 'stained glass'
Carbon nanotubes are promising materials for many high-technology applications due to their exceptional mechanical, thermal, chemical, optical and electrical properties.
Memory in artificial atoms
Three of our nano-physicists have made a discovery that can change the way we store data on our computers. This means that in the future we can store data much faster, and more accurate. Their discovery has been published in the scientific journal Nature Physics.
The future of computing -- carbon nanotubes and superconductors to replace the silicon chip
The future of computing is under the spotlight at the Institute of Physics' Condensed Matter and Materials Physics conference at the Royal Holloway College of the University of London on 26-28 March.
Carbon nanotubes outperform copper nanowires as interconnects
Researchers at Rensselaer Polytechnic Institute have created a road map that brings academia and the semiconductor industry one step closer to realizing carbon nanotube interconnects, and alleviating the current bottleneck of information flow that is limiting the potential of computer chips in everything from personal computers to portable music players.
NRL scientists produce carbon nanotubes using commercially available polymeric resins
Scientists at the Naval Research Laboratory (NRL) have successfully produced carbon nanotubes (CNTs) in high yields in bulk solid compositions using commercially available aromatic containing resins.
Researchers develop darkest manmade material
Researchers at Rensselaer Polytechnic Institute and Rice University have created the darkest material ever made by man.
Improved wettability of carbon nanotubes opens the door to new possibilities
Carbon nanotubes have long been touted as the wonder material of the future but their wonder properties can also be their downfall. The non reactive nature of carbon nanotubes means they can be difficult to incorporate into other materials for real world applications.
World's Smallest Radio Fits in the Palm of the Hand . . . of an Ant
Harnessing the electrical and mechanical properties of the carbon nanotube, a team of researchers has crafted a working radio from a single fiber of that material.
Make Way for the Real Nanopod: Berkeley Researchers Create First Fully Functional Nanotube Radio
Make way for the real nanopod and make room in the Guinness World Records. A team of researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have created the first fully functional radio from a single carbon nanotube, which makes it by several orders of magnitude the smallest radio ever made.
More Carbon Nanotube News Articles
 | Physical Properties of Carbon Nanotubes by R. Saito |
 | Carbon Nanotubes: Properties and Applications |
 | Carbon Nanotubes: Science and Applications |
 | Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications (Topics in Applied Physics) |
 | Carbon Nanotubes: Basic Concepts and Physical Properties by Stephanie Reich, Christian Thomsen, Janina Maultzsch |
 | Physics of Carbon Nanotube Devices (Micro & Nano Technologies) by Francois Leonard |
 | Micromanufacturing and Nanotechnology by N.P. Mahalik |
 | Carbon Nanotubes and Related Structures by Peter J. F. Harris |
 | One-Dimensional Metals: Conjugated Polymers, Organic Crystals, Carbon Nanotubes by Siegmar Roth, David Carroll |
 | Carbon Nanotubes: Synthesis, Structure, Properties and Applications |
| © 2008 BrightSurf.com |