Tuesday, May 06, 2008

Nanowires for Displays

Continued from page 1

By Prachi Patel-Predd

Companies such as Sony and Motorola first tried to commercialize field-emission displays about 10 years ago. Those displays used micrometer-sized metal tips as electron emitters. But the tips required high voltages and couldn't be made on large areas. Some manufacturers then shifted attention to carbon nanotubes. Both Samsung and Motorola have developed carbon nanotube-based FED technology (see "Nanotech on Display" and "High-Definition Carbon Nanotube TVs"). Field Emission Technologies, a Sony spin-off, is taking a different approach. They are using metal nanotips as emitters. The company plans to ship professional FED video monitors based on this technology in 2009.

But all of these displays are expensive and are still not ready for the commercial TV market. The reason for that is both economical and technical, says David Barnes, an analyst at DisplaySearch, a consultancy in Austin, TX. One of the key technological barriersis to create and maintain a vacuum between the electron emitters and the phosphor-coated glass. The emitters can also degrade over time due to the extremely high energies forming at their tips. Maintaining both the vacuum and the emitters for a TV's 10-year life is a challenge.

Field-emission displays that use copper nanowires will face the same problems. However, says Barnes, copper ".might be a little more robust."

Chris Chinock, founder and president of Insight Media, a Norwalk, CT-based consulting firm that focuses on the display industry, calls the new development a promising research result, although too early-stage "to put on our radar just yet." He points out that the nanowires will have to be thinner than 70- to 250-nanometers. Carbon nanotubes and metal nanotips are only a few nanometers big, resulting in 10,000 or more emitters at each pixel. Even if half of them do not work, there are still enough to light up the pixel.

While the industry is not expecting commercial FED displays out any time soon, Barnes says that more research on different new technologies is warranted. "When people have made lab prototypes it's pretty compelling," he says. "There is this bright aliveness that you would get from watching a traditional CRT."