Tomorrow's world will have everlasting light

The world of electronics is buzzing with excitement about what scientists are calling the most important new material since silicon. Potential applications of gallium nitride range from everlasting light bulbs to featherweight mobile phones, from heat-proof computer chips for car engines to music systems that could store all Chopin's work on a single disc.

Colin Humphreys, professor of materials science at Cambridge University, says gallium nitride - a man-made semiconductor - "will revolutionise many areas of electronics".

Much of gallium nitride's appeal lies in the fact that it glows intensely when an electric current is applied. By adding varying amounts of indium, another chemical element, to the material, scientists can make it glow any colour or, with a phosphor coating, give white light.

A light-emitting diode (LED) made from gallium nitride consumes only one-fifth as much electricity as a conventional bulb, because it does not waste energy heating up an incandescent filament. And it lasts 100 times longer.

These properties will be exploited first in traffic lights, says Prof Humphreys. "A rough calculation shows that the energy consumption of all Britain's traffic lights is equivalent to the output of two medium-sized power stations - and we'll be able to save 80 per cent of that."

Gallium nitride is being tested in experimental traffic lights in Marsham Street, London, and at the end of the M32 motorway in Bristol. Road users comment favourably on the clear, bright signals. Highways authorities are attracted by prospective saving in maintenance costs, since conventional tungsten halogen bulbs need replacing twice a year while gallium nitride LEDs will last for 10 years.

In Japan, gallium nitride already illuminates giant electronic billboards and advertising displays. It is also likely to take over from other semiconductors in low-level LED applications, for example in instrumentation.

But the biggest long-term market may be for domestic and office lighting, instead of incandescent bulbs and fluorescent tubes. "With normal intermittent use gallium nitride lamps would last a lifetime," Prof Humphreys says. "Once fitted, you may never have to change another bulb."

The lighting industry has been accused in the past of killing research and development that could have led to an everlasting bulb. But the main bulb manufacturers are investing in gallium nitride technology, knowing that if they do not offer products in this area, others will step in.

For example Philips, the giant Dutch lighting and electronics company, has a joint venture with Hewlett-Packard of the US to promote LED lighting. The two partners are investing an initial $150 million (€140 million) in the venture. Even so, Philips does not see gallium nitride making big inroads into the domestic lighting market for 10 to 20 years because LED lamps are still much more expensive than bulbs made with 120-year-old incandescent filament technology.

Another huge market, which will probably open up more quickly, is gallium nitride lasers to read and write CDs and other digital discs. Today's music and computer storage systems use red lasers to burn tiny holes, representing 0s and 1s, in the disc surface. Gallium nitride will provide, for the first time, blue lasers. These operate at shorter wavelengths, allowing smaller holes to be written and read reliably. Storage densities will increase fourfold as a result.

There is great potential, too, in the material's non-optical electronic properties. For example, gallium nitride chips can operate at much higher power and shorter wavelengths than the transistors used in today's mobile phones. These will enable manufacturers to give mobiles a greater range in future.

Yet another virtue of gallium nitride - its ability to operate at much higher temperatures than silicon - is especially important for the auto and aerospace industries. Silicon chips have to be placed well away from a car or aircraft engine, because they cannot stand the heat. Gallium nitride will be mounted directly on the engine, making the electronic control more efficient.

Although the whole electronics industry is now working on gallium nitride, its emergence as a key material for the next century is a triumph above all for the innovative spirit of Japan. Through long-term perseverance over the past 15 years, Nichia Chemical Industries, a small Japanese company, has managed to overcome the production problems that had previously prevented electronic engineers working with gallium nitride, despite its theoretical advantages.

Many people still imagine that Japan has contributed little to the world's scientific and industrial development, beyond a genius for copying and mass-producing other people's work. If the Sony Walkman did not banish that idea, gallium nitride should.