Navigation Links
Small ... smaller ... smallest? ASU researchers create molecular diode
Date:10/13/2009

Recently, at Arizona State University's Biodesign Institute, N.J. Tao and collaborators have found a way to make a key electrical component on a phenomenally tiny scale. Their single-molecule diode is described in this week's online edition of Nature Chemistry.

In the electronics world, diodes are a versatile and ubiquitous component. Appearing in many shapes and sizes, they are used in an endless array of devices and are essential ingredients for the semiconductor industry. Making components including diodes smaller, cheaper, faster and more efficient has been the holy grail of an exploding electronics field, now probing the nanoscale realm.

Smaller size means cheaper cost and better performance for electronic devices. The first generation computer CPU used a few thousand transistors, Tao says noting the steep advance of silicon technology. "Now even simple, cheap computers use millions of transistors on a single chip."

But lately, the task of miniaturization has gotten much harder, and the famous dictum known as Moore's lawwhich states that the number of silicon-based transistors on a chip doubles every 18-24 monthswill eventually reach its physical limits. "Transistor size is reaching a few tens of nanometers, only about 20 times larger than a molecule," Tao says. "That's one of the reasons people are excited about this idea of molecular electronics."

Diodes are critical components for a broad array of applications, from power conversion equipment, to radios, logic gates, photodetectors and light-emitting devices. In each case, diodes are components that allow current to flow in one direction around an electrical circuit but not the other. For a molecule to perform this feat, Tao explains, it must be physically asymmetric, with one end capable of forming a covalent bond with the negatively charged anode and the other with the positive cathode terminal.

The new study compares a symmetric molecule with an asymmetric one, detailing the performance of each in terms of electron transport. "If you have a symmetric molecule, the current goes both ways, much like an ordinary resistor," Tao observes. This is potentially useful, but the diode is a more important (and difficult) component to replicate (Fig 1).

The idea of surpassing silicon limits with a molecule-based electronic component has been around awhile. "Theoretical chemists Mark Ratner and Ari Aviram proposed the use of molecules for electronics like diodes back in 1974," Tao says, adding "people around world have been trying to accomplish this for over 30 years."

Most efforts to date have involved many molecules, Tao notes, referring to molecular thin films. Only very recently have serious attempts been made to surmount the obstacles to single-molecule designs. One of the challenges is to bridge a single molecule to at least two electrodes supplying current to it. Another challenge involves the proper orientation of the molecule in the device. "We are now able to do thisto build a single molecule device with a well defined orientation," Tao says.

The technique developed by Tao's group relies on a property known as AC modulation. "Basically, we apply a little periodically varying mechanical perturbation to the molecule. If there's a molecule bridged across two electrodes, it responds in one way. If there's no molecule, we can tell."

The interdisciplinary project involved Professor Luping Yu, at the University of Chicago, who supplied the molecules for study, as well as theoretical collaborator, Professor Ivan Oleynik from the University of South Florida. The team used conjugated molecules, in which atoms are stuck together with alternating single and multiple bonds. Such molecules display large electrical conductivity and have asymmetrical ends capable of spontaneously forming covalent bonds with metal electrodes to create a closed circuit.

The project's results raise the prospect of building single molecule diodes the smallest devices one can ever build. "I think it's exciting because we are able to look at a single molecule and play with it, " Tao says. "We can apply a voltage, a mechanical force, or optical field, measure current and see the response. As quantum physics controls the behaviors of single molecules, this capability allows us to study properties distinct from those of conventional devices."

Chemists, physicists, materials researchers, computational experts and engineers all play a central role in the emerging field of nanoelectronics, where a zoo of available molecules with different functions provide the raw material for innovation. Tao is also examining the mechanical properties of molecules, for example, their ability to oscillate. Binding properties between molecules make them attractive candidates for a new generation of chemical sensors. "Personally, I am interested in molecular electronics not because of their potential to duplicate today's silicon applications, " Tao says. Instead, molecular electronics will benefit from unique electronic, mechanical, optical and molecular binding properties that set them apart from conventional semiconductors. This may lead to applications complementing rather than replacing silicon devices.


'/>"/>

Contact: Joe Caspermeyer
joseph.caspermeyer@asu.edu
480-727-0369
Arizona State University
Source:Eurekalert  

Related biology technology :

1. Imagenetix Inc. to Present at Noble Small Cap Financial Conference on August 21, 2007
2. FDA Approves ACAM2000(TM) Vaccine for Protection Against Smallpox
3. Exelixis Reports Encouraging Interim Data From a Phase 2 Trial of XL647 as First-Line Therapy for Non-Small Cell Lung Cancer
4. Stimuvax(R) Phase II data highlight three-year survival results for patients with non-small cell lung cancer
5. New technique producing small things in large quantities
6. Small Bone Innovations Introduces the Artelon(R) STT Spacer to Increase Treatment Options for Thumb Arthritis
7. Cell Therapeutics, Inc. (CTI) Receives SPA Approval from FDA and Launches Gender-Specific Phase III Trial for Advanced Non-Small Cell Lung Cancer
8. Small Bone Innovations Introduces New Distal Radius Plating System to Repair Complex Fractures
9. Cepheid to Present at William Blair Small-Cap Growth Stock Conference
10. Government Expands Trial With IMVAMUNE(R) Smallpox Vaccine in Persons With Atopic Dermatitis/Eczema
11. Poniard Pharmaceuticals Announces European Commission Grants Orphan Medicinal Product Designation to Picoplatin for Treatment of Small Cell Lung Cancer
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Small ... smaller ... smallest? ASU researchers create molecular diode
(Date:10/11/2017)... (PRWEB) , ... October 11, 2017 , ... Disappearing forests ... the lives of over 5.5 million people each year. Especially those living in larger ... startup Treepex - based in one of the most pollution-affected countries globally - decided ...
(Date:10/10/2017)... ... 10, 2017 , ... For the second time in three ... Mentoring Award. Representatives of the FirstHand program travelled to Washington, D.C. Tuesday, October ... US2020’s mission is to change the trajectory of STEM education in America by ...
(Date:10/10/2017)... , ... October 10, 2017 , ... ... of 13 prestigious awards honoring scientists who have made outstanding ... a scheduled symposium during Pittcon 2018, the world’s leading conference and exposition for ...
(Date:10/9/2017)... (PRWEB) , ... October 09, ... ... published on October 5, 2017, in the medical journal, Epilepsia, Brain Sentinel’s ... the gold standard, video EEG, in detecting generalized tonic-clonic seizures (GTCS) using ...
Breaking Biology Technology:
(Date:3/30/2017)... -- Trends, opportunities and forecast in this market to ... AFIS, iris recognition, facial recognition, hand geometry, vein recognition, ... industry (government and law enforcement, commercial and retail, health ... and by region ( North America , ... , and the Rest of the World) ...
(Date:3/27/2017)... ROCKVILLE CENTRE, N.Y. , March 27, 2017 ... by Healthcare Information and Management Systems Society (HIMSS) ... Analytics Outpatient EMR Adoption Model sm . In ... top 12% of U.S. hospitals using an electronic ... recognized CHS for its high level of EMR ...
(Date:3/23/2017)... The report "Gesture Recognition and Touchless Sensing Market by Technology (Touch-based and ... 2022", published by MarketsandMarkets, the market is expected to be worth USD 18.98 ... Continue Reading ... ...      ...
Breaking Biology News(10 mins):