New Thin-Film Transistor Can Enhance Laptop Computer Displays

June 03, 1997

CHAMPAIGN, Ill. - A new type of thin-film transistor developed at the University of Illinois could improve the resolution of flat-panel, liquid-crystal displays used in laptop computers. The transistor contains a novel "buried channel" that allows electrons to move faster, permitting much higher switching speeds.

"In conventional thin-film transistors, electrons travel near the semiconductor-insulator interface, where the silicon is strained and is of poor quality," said John R. Abelson, a U. of I. professor of materials science and engineering. "By creating a buried conducting channel, recessed about 50 angstroms away from the interface, we can increase the speed of the electrons and significantly enhance the performance of devices built with these transistors."

Flat-panel displays consist of hundreds of thousands of pixels, each controlled by a thin-film transistor. While the performance of these displays is adequate at present, future applications that require higher resolution (such as high-definition television or enhanced computer displays) will be limited by the speed at which the transistors can be turned on and off.

"Higher resolution means adding more pixels," Abelson said. "But as the number of pixels rises, there is less time to address each one and still produce a complete image at standard video rates."

Because the buried channel is placed in a region of higher-quality material, electrons can move through the device nearly twice as fast as they normally would, Abelson said. "This means it would take significantly less time to deliver the necessary charge to turn a pixel on or off, so you could address many more pixels in the same amount of time."

To fabricate the buried channel thin-film transistors, Abelson and graduate student Cory Weber use a technique called reactive magnetron sputtering. This method -- which uses a plasma to erode a silicon target and deposit a film -- provides precise control over layer composition and electronic properties.

"To create a step in the conduction band, and thus a buried channel, we vary the amount of hydrogen gas injected into the plasma while we deposit the amorphous silicon layer," Abelson said.

The sputtering technique also allows films to be deposited at much lower temperatures than currently possible with the plasma-enhanced chemical-vapor-deposition process used by industry.

"We have fabricated these transistors at a processing temperature of 125 degrees C," Abelson said. "This opens up the possibility of using lightweight and impact-resistant plastic substrates in place of the glass substrates currently employed. Production systems using reactive magnetron sputtering have recently been developed by the Intevac Corporation based on our results."

Abelson and Weber describe the fabrication and operation of the new transistor in the September issue of the Journal of Vacuum Science and Technology. A patent has been applied for.
-end-


University of Illinois at Urbana-Champaign

Related Electrons Articles from Brightsurf:

One-way street for electrons
An international team of physicists, led by researchers of the Universities of Oldenburg and Bremen, Germany, has recorded an ultrafast film of the directed energy transport between neighbouring molecules in a nanomaterial.

Mystery solved: a 'New Kind of Electrons'
Why do certain materials emit electrons with a very specific energy?

Sticky electrons: When repulsion turns into attraction
Scientists in Vienna explain what happens at a strange 'border line' in materials science: Under certain conditions, materials change from well-known behaviour to different, partly unexplained phenomena.

Self-imaging of a molecule by its own electrons
Researchers at the Max Born Institute (MBI) have shown that high-resolution movies of molecular dynamics can be recorded using electrons ejected from the molecule by an intense laser field.

Electrons in the fast lane
Microscopic structures could further improve perovskite solar cells

Laser takes pictures of electrons in crystals
Microscopes of visible light allow to see tiny objects as living cells and their interior.

Plasma electrons can be used to produce metallic films
Computers, mobile phones and all other electronic devices contain thousands of transistors, linked together by thin films of metal.

Flatter graphene, faster electrons
Scientists from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel developed a technique to flatten corrugations in graphene layers.

Researchers develop one-way street for electrons
The work has shown that these electron ratchets create geometric diodes that operate at room temperature and may unlock unprecedented abilities in the illusive terahertz regime.

Photons and electrons one on one
The dynamics of electrons changes ever so slightly on each interaction with a photon.

Read More: Electrons News and Electrons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.