Featured Research

from universities, journals, and other organizations

High-performance, Single-crystal Plastic Transistors Reveal Hidden Behavior

Date:
March 12, 2004
Source:
University Of Illinois At Urbana-Champaign
Summary:
Printing circuits on sheets of plastic may offer a low-cost technique for manufacturing thin-film transistors for flexible displays, but maximizing the performance of such devices will require a detailed, fundamental understanding of how charge flows through organic semiconductors.

CHAMPAIGN, Ill. -- Printing circuits on sheets of plastic may offer a low-cost technique for manufacturing thin-film transistors for flexible displays, but maximizing the performance of such devices will require a detailed, fundamental understanding of how charge flows through organic semiconductors.

Related Articles


Now, an unusual way of fabricating single-crystal organic transistors has allowed scientists to probe charge transport within the crystals and to observe a strong anisotropy of the charge transport mobility within the crystal plane never before seen.

"We construct transistors simply by laminating a piece of silicone rubber that supports electrodes and dielectric layers for the transistor -- an element that we refer to as a transistor stamp -- against the surface of a single crystal," said John A. Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign and corresponding author of a paper to appear in the March 12 issue of the journal Science.

"This method separates the synthesis of the crystal from the fabrication of the other elements needed for the transistors," Rogers said. "It thereby eliminates exposure of the fragile surface of the organic crystals to the hazards of conventional processing."

The fabrication technique -- developed by researchers from Illinois, Rutgers University and Bell Laboratories, Lucent Technologies -- not only provides a way to study the physics at the heart of charge transport in these unusual materials, it also has resulted in the highest mobility recorded in an organic semiconductor. The use of transistor stamps promises to open up the field of basic study of organic semiconductors by allowing devices to be fabricated from pristine organic crystal samples that remain untouched by conventional chemical or mechanical processing.

To build their high-performance organic transistors, the researchers start with a simple rubber substrate, upon which they deposit gold films and thin rubber layers to create the gate dielectric and the source, drain and gate electrodes. A high-quality rubrene crystal -- grown by the Rutgers group -- is then bonded to the substrate to complete assembly. The bonding is performed by a lamination process carried out in ambient conditions without pressure or adhesives.

"While this assembly process could be performed commercially to produce complex circuits, we really designed it to get at the physics," Rogers said. "Understanding the fundamental behavior of charge transport in these transistors will help us make better devices for the wide range of electronic applications that are now emerging for these classes of materials."

As charges flow through conventional thin-film polycrystalline materials, they encounter boundaries between the crystals that disrupt their movement. By studying single crystals, Rogers and his colleagues can eliminate the effects of these grain boundaries and examine the intrinsic transport properties of the crystalline material itself.

"The mobility we measured in these single-crystal devices was about 50 to 100 times larger than in thin-film plastic transistors," Rogers said. "This result suggests that scattering at grain boundaries is significantly reducing the performance of normal transistors, and points us toward a way of improving these devices."

Because the bond between stamp and crystal is not permanent, the researchers also can remove the crystal, rotate it, and reattach it to the substrate. Repositioning the crystal allows the scientists to explore the dependence of the mobility on the orientation of the transistor channel relative to the crystal axes.

"We found a huge dependence upon transport direction in the currents that we measured," Rogers said. "This anisotropy was unexpected, and indicates that transistor performance depends strongly on how the electrodes are oriented relative to the packing of molecules in the crystal."

The researchers' findings have clear device implications. In addition to removing grain boundaries, Rogers said, "if you could preferentially order the crystals in these thin films, that would benefit device performance as well."

Collaborators included Vitaly Podzorov and Michael E. Gershenson at Rutgers, Vikram C. Sundar, Jana Zaumseil, Robert L. Willett and Takao Someya at Bell Labs, and Etienne Menard at Illinois.

The National Science Foundation and the U.S. Department of Energy funded the work.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "High-performance, Single-crystal Plastic Transistors Reveal Hidden Behavior." ScienceDaily. ScienceDaily, 12 March 2004. <www.sciencedaily.com/releases/2004/03/040312090304.htm>.
University Of Illinois At Urbana-Champaign. (2004, March 12). High-performance, Single-crystal Plastic Transistors Reveal Hidden Behavior. ScienceDaily. Retrieved November 21, 2014 from www.sciencedaily.com/releases/2004/03/040312090304.htm
University Of Illinois At Urbana-Champaign. "High-performance, Single-crystal Plastic Transistors Reveal Hidden Behavior." ScienceDaily. www.sciencedaily.com/releases/2004/03/040312090304.htm (accessed November 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com
NSA Director: China Can Damage US Power Grid

NSA Director: China Can Damage US Power Grid

AP (Nov. 20, 2014) China and "one or two" other countries are capable of mounting cyberattacks that would shut down the electric grid and other critical systems in parts of the United States, according to Adm. Michael Rogers, director of the National Security Agency and hea Video provided by AP
Powered by NewsLook.com
Latest Minivan Crash Tests Aren't Pretty

Latest Minivan Crash Tests Aren't Pretty

Newsy (Nov. 20, 2014) Five minivans were put to the test in head-on crash simulations by the Insurance Institute for Highway Safety. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins