Scientists from Lucent Technologies' Bell Labs have created organic transistors with a single-molecule channel length, setting the stage for a new class of high-speed, inexpensive carbon-based electronics.
The size of a transistor's channel -- the space between its electrodes -- influences its output current and switching speed.
In these new molecular-scale transistors, fabricated by a multidisciplinary team of Bell Labs researchers, the length of one molecule defines the channel's physical dimension; it is more than a factor of ten smaller than anything that has been demonstrated even with the most advanced lithography techniques.
The breakthrough is reported in the October 18th issue of the journal Nature.
Scientists have been looking for alternatives to conventional silicon electronics for many years, because they anticipate that the continuing miniaturization of silicon-based integrated circuits will subside in approximately a decade as fundamental physical limits are reached.
Some of this research has been aimed at producing molecular-scale transistors, in which single molecules are responsible for the transistor action - switching and amplifying electrical signals.
"When we tested them, they behaved extremely well as both amplifiers and switches," said Schon, an experimental physicist who was the lead researcher.
Using the tiny transistors, which are roughly a million times smaller than a grain of sand, the team built a voltage inverter, a standard electronic circuit module, commonly used in computer chips, that converts a "0" to a "1" or vice versa.
Though just a prototype, the success of the simple circuit suggests that molecular-scale transistors could one day be used in microprocessors and memory chips, squeezing thousands of times as many transistors onto each chip than is possible today.
The main challenges in making molecular-scale transistors are fabricating electrodes that are separated by only a few molecules and attaching electrical contacts to the tiny devices. The Bell Labs researchers were able to overcome these hurdles by using a self-assembly technique and a clever design in which each electrode is shared by many transistors.
"We solved the contact problem by letting one layer of organic molecules self-assemble on one electrode first, and then placing the second electrode above it," said Bao, an organic chemist. "For the self assembly, we simply make a solution of the organic semiconductor, pour it on the base, and the molecules do the work of finding the electrodes and attaching themselves."
"This is a beautiful, simple and clever approach," said Professor Paul Weiss of the Pennsylvania State University, an expert in molecular electronics. "It circumvents many of the difficulties inherent in other nanofabrication approaches."
The chemical self-assembly technique is relatively easy and inexpensive, but is key to reducing the transistor's channel length. The channel length of the experimental transistors is between one and two nanometers (billionths of a meter), an order of magnitude smaller than any transistor channel created before.
William Shockley, John Bardeen and Walter Brattain invented the transistor at Bell Labs in 1947. Their invention spawned the digital age and earned them the Nobel Prize for Physics in 1956.
Over the years, Bell Labs scientists have made many of the important contributions that have helped make transistors smaller, faster and more powerful. The technology curve has culminated with the latest development of molecular-scale transistors.
"The molecular-scale transistors that we have developed may very well serve as the historical 'bookend' to the transistor legacy started by Bell Labs in 1947," said Federico Capasso, physical research vice president at Bell Labs.
Background on Molecular-scale Transistors
Subscribe To SpaceDaily Express
TECH SPACENanotechnology Gets A Boost With Purchase Of EB System At JPL
Pasadena - April 23, 2001
In the forefront of nanotechnology development, NASA's Jet Propulsion Laboratory in Pasadena, Calif., has acquired one of the world's finest electron beam lithography systems, one that will allow researchers to work on the sub-molecular scale.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|