Diamond LED sparks laser hopes

17 Jun 2002

Japanese scientists have moved a step closer to diamond lasers by developing ultraviolet diamond LEDs.

Japan-based researchers have fabricated an ultraviolet-light-emitting diode (LED) using diamond thin films, (Science 292 1899-1901). This important milestone in diamond electronics could pave the way to a new wave of lasers and high-density data storage.

Satoshi Koizumi from the National Institute for Materials Science, Ibaraki, and colleagues created the diode by epitaxially growing diamond layers on a single diamond crystal. To form the diode's pn junction, the team added boron - a "p-type dopant" - which snatches electrons from the diamond's lattice, to the first film. The researchers also added phosphorous - an electron donator or "n-type dopant" - to the second film.

The researchers went on to test the diode's light-emitting properties by applying increasing voltages to it. At low voltages, the team noticed light emissions over a range of frequencies, but at 20 V the diode emitted ultraviolet light. By achieving this feat, the researchers are among the first in the world to develop and fabricate an operational diamond LED.

Koizumi and his colleagues now wish to build on their results. "By further improving the crystalline quality of the boron-doped diamond layer, [extraneous] emissions will be suppressed," said Koizumi. "This means that a diamond LED that exclusively emits monochromatic ultraviolet light of 235 nm will be feasible."