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Transparent Screens on the Horizon?
mhesseltine writes "According to United Press, researchers in Japan are developing transparent transistors. This could bring about see-through screens like those in Minority Report. Also, I imagine would be better heads-up displays (HUDs) for vehicles, layered flat panel displays, and new methods of interfacing with information screens."
Transparent TVs from invisible circuits
UPI Science News
From the Science & Technology Desk
Published 5/22/2003 2:59 PM
YOKOHAMA, Japan, May 22 (UPI) -- Scientists said Thursday that invisible, high-speed circuitry from Japan someday soon could form the innards of devices now seen only in science fiction, such as televisions made of nothing but hunks of transparent crystal.
"Transparent transistors are the first step towards the realization of transparent displays, such as seen in Tom Cruise's last summer movie, 'Minority Report,'" electrical engineer John Wager of Oregon State University in Corvallis told United Press International. "I was astonished when I first heard about this result."
Inventors have used invisible conductors of electricity in gadgetry for years. Clear wires that heat up when electrified help defrost car windows. See-through films carry voltage and underlie computer touch screens.
However, if scientists can weave these invisible conductors to make transparent circuitry, they could brighten the laptop industry and other billion-dollar markets, Wager explained. The most common types of flat panel displays are called active matrix liquid crystal displays, or AMLCDs.
"Each of the hundreds of thousands to tens of millions of picture elements or pixels in an AMLCD has a select transistor used to turn the pixel on or off," Wager explained. "These transistors are opaque, and light-sensitive; thus, light shielding of these transistors is required."
Replacing these conventional circuits with transparent ones would allow "more light to pass through each pixel. Thus, transparent transistors have the potential to make AMLCDs brighter and more efficient. Considering that AMLCDs currently constitute a roughly $10-billion-to-$15-billion-a-year market, this one application alone could have a big impact," Wager said. "AMLCDs are perhaps the big, '300-pound gorilla' application."
See-through electronic displays could help car drivers read out information or shop owners advertise wares. "I just gave an invited talk in Orlando at a military electronics meeting," Wager said. "There seemed to be a lot of interest -- however, no one wanted to tell me exactly why they were so interested."
Wager and his team invented the first clear transistor, which they reported in March, although they were not high-performance enough for display applications, he said.
In findings appearing in the May 23 issue of the journal Science, researchers at the Tokyo Institute of Technology in Yokohama revealed invisible circuits at least 10 times faster than any seen before.
"I was flabbergasted," Wager said, who did not participate in the research. Like Wager's transistors, the researchers used oxides, or minerals containing oxygen.
"Oxides are traditional materials represented by porcelain, rich in resources and environmental friendly," said research leader Hideo Hosono.
The strength of the new transistors has to do with mobility, or how well electrons move in a solid when driven by an electric field. Although earlier transparent circuits only had a mobility of up to 2.5 or so, the new transistors have a mobility of 80.
"If you had asked me about the theoretical upper bound before this, I would've guessed 20 or 30 -- with 50 as a crazy limit," Wager said.
The secret of the new transistors is they are made of single crystals. Earlier transistors were poly-crystalline, that is, they were composed of many tiny single crystals lumped together. That construction approach is problematic because whenever electrons must hop from crystal to crystal, they slow down.
Mass production of these new single crystal transistors probably is far off. They are made with expensive, finicky lasers that vaporize the raw ingredients of the circuits to grow them in crystalline form on surfaces, a process known as pulsed laser deposition. Also, creating the chips requires temperatures of more than 2,500 degrees Fahrenheit, whil