Osram Opto develops blue thin-film InGaN LEDs
In the world s first production-scale laser lift-off plant, the light from a pulsed UV laser separates the InGaN-based layers from the sapphire substrate (see diagram).
In contrast, SiC is chemically and mechanically very stable, and cannot be removed (using either a wet chemical process or a dry chemical plasma process) without also destroying the thin InGaN epitaxial layer.
Other key factors for the exceptionally high efficiency of these ThinGaN LEDs are the optimized surface roughness, low optical losses in the LED itself and mirror metalization as a reflector tailored to this material combination.
Prototypes of 5 mm-radial LEDs achieve brightness values of up to 16 mW for the blue products (460 nm) at an operating current of 20 mA.
The company expects to commence production of blue thin-film LEDs in 2004.
