Future Looks Bright for Notebook Displays
Gallium nitride could lead to more vivid screens that require less power--and it could even be used to fight terrorism.
Stephen Lawson, IDG News Service
LAS VEGAS -- Notebook and color phone displays could be more vivid and suck up less power, and mobile phone base stations could be cut down to shoebox size, with an old semiconductor material that's attracting new interest, researchers said here Tuesday in a session at the Comdex trade show.
Gallium nitride, or GaN, first used in labs more than 30 years ago, is now used commercially for blue semiconductor lasers that can read high-capacity disks called Blu-Ray DVDs. Within a few years it should become a practical material for LCD backlights, wireless communications processors, and even devices that detect dangerous biological materials such as anthrax, the panelists said.
The backlights that illuminate most LCDs today are cold-cathode fluorescent lights, which convert only about 24 percent of their electrical power into light (with the rest becoming heat). GaN can be much more efficient, converting as much as 30 percent of the power into light now, and probably as much as 50 percent in a few years, said Steven DenBaars, a materials engineering professor at the University of California at Santa Barbara who participated in the panel. That means batteries can last longer and devices with LCDs will create less heat, which can reduce the hardware's longevity, he said.
Ray of Light
"GaN will be the most efficient light source on the planet," DenBaars said. As an example of what can be achieved, he showed off a GaN flashlight which he said can last 100 hours on a set of batteries that would last just 20 hours in a typical flashlight. The technology has also been tested in auto headlights.
In addition, because of the kind of light it can produce, a GaN light source also allows for displays that show more colors, he said. A GaN light source also can last longer than a fluorescent source because it's purely solid state--it's just a crystal, DenBaars said.
Today, a GaN backlight for a typical 14-inch notebook display costs about $100 to make, he said. Within a few years, that cost should fall to become comparable with current fluorescent lights.
GaN shows promise as an efficient, long-lasting backlight technology, said Peter Glaskowsky, principal analyst at In-Stat/MDR, in San Jose, California. LED backlights like those made with GaN probably will initially be easier for manufacturers to use in handheld displays, because lighting a whole notebook LCD from diodes around the edge is a challenge, he added.
Plenty of Possibilities
The technology currently is used for blue lasers in DVD readers with the Blu-Ray technology, which was proposed by a consortium of drive vendors earlier this year. The discs that go into those players can hold as much as 27GB of data, compared with about 4.7GB for a typical DVD. GaN makes that possible because a blue GaN laser can read a larger number of smaller data points crammed onto a disc. Because of the cost of the lasers, those drives cost $500 to $1,000 today but are likely to hit consumer-friendly price levels in about two years, DenBaars predicted.
That same capability of focusing on a small spot opens up the possibility of laser printers that can produce a greater density of pixels for much sharper documents, said Noble Johnson, a principal scientist at Palo Alto Research Center, a Palo Alto, California, subsidiary of Xerox.
GaN also shows promise in biological security, Johnson added. It's a smaller, less power-hungry alternative to current tools for laser-induced fluorescence, in which a laser lights up a liquid solution to reveal a biological agent by color. With GaN as a laser, devices that detect dangerous agents such as anthrax could become much smaller and more easily portable, he said.
As a semiconductor, GaN can provide greater communications bandwidth than other materials, said John Palmour, director of advanced devices at Cree, in Durham, North Carolina. It may allow cellular base station makers to use a single chip for mobile phone frequencies all the way from 1800 MHz through Universal Mobile Telecommunications System, a form of 3G mobile data technology. One barrier that needs to be overcome for this application is GaN's tendency to degrade in power over time, he added.
Making it work could mean mobile base stations shrinking down from full-size refrigerator scale to shoebox size and consuming much less power, UC Santa Barbara's DenBaars said.
