Groovy LEDs make brighter lights

Researchers at the US

(NIST) have made semiconductor light-emitting diodes (LEDs) more than seven times brighter. They achieved this by etching nanoscale grooves in a surrounding cavity to guide scattered light in one direction. The nanostructured devices may have applications in areas such as in biomedical imaging, where LED brightness is crucial.

Semiconductor LEDs are used increasingly in displays and many other applications, in part because they can efficiently produce light across a broad spectrum, from near-infrared to the ultraviolet. However, they typically emit only about two per cent of the light in the desired direction - perpendicular to the diode surface. Far more light skims uselessly below the surface of the LED, because of the mismatch in refraction between air and the semiconductor.

The NIST nanostructured cavity boosts useful LED emission to about 41 per cent and may be cheaper and more effective for some applications than conventional post-processing LED shaping and packaging methods that attempt to redirect light.