Japanese boffins claim ultraviolet breakthrough

A breakthrough in fundamental technology behind devices like LEDs and lasers could lead to advances in a wide range of products, including optical disks, light sources and flat-panel displays.

Scientists at Japan's National Institute of Advanced Industrial Science and Technology claim to have developed a new highly efficient ultraviolet light emitting semiconductor. 

"These results provide the way to high-density optical data processing, highly efficient and long-life white light sources, and high-performance large-area transparent conducting thin films for solar cells and flat-panel displays," said the researchers.

Semiconductors that emit light at very short wavelengths have hitherto proven difficult to develop.

The wavelength of light determines the colour. For example red light has a relatively long wavelength, while green, blue, violet and ultraviolet light have progressively shorter wavelengths.

Short-wavelength light has a number of advantages over longer wavelengths, including the ability to read and write data more compactly on optical disks.

This is why recent high capacity optical storage systems, such as Blu-Ray and HD-DVD, use blue semiconductor lasers.

The new technology relies on a zinc oxide compound combined with minute quantities of magnesium oxide. This is claimed to offer several advantages over existing materials used for similar devices.

"The luminescence efficiency of the conventional semiconductors, including the gallium nitride that has been used in practical blue-light emitting diodes, generally decreases with the wavelength of the emitted light, and hence it is hard to realise light emitting diodes that work in the ultraviolet wavelength region," the researchers said.

Unlike other technologies, the Japanese researchers claim that their ultraviolet semiconductor will have a long lifespan as well as making efficient use of power. Further improvements in light output are possible, they predict.