17 Jun 2002
A unique production process promises to bring cheaper, brighter, blue-emitting LEDs to the market.
US-based start-up Oriol has developed a new design of high-brightness light-emitting diode (HB-LED). Applied to the gallium nitride (GaN) material system, it results in cheaper and brighter blue-emitting devices for applications such as traffic signals, outdoor video signs and solid-state lighting.
Oriol grows GaN on a sapphire substrate. A thermally and electrically conductive metal layer is then bonded on top of the GaN. The LED structure is removed from the sapphire using a proprietary lift-off technique, leaving the GaN and the reflective base ready for the fabrication of vertical devices.
"This vertical device differentiates Oriol from other HB-LED chip makers," said Oriol's president G. Burt Lancaster. "Customers now have an alternative to silicon carbide and sapphire-based devices which require special handling and have limited performance."
The low thermal resistance and high electrical conductivity of the metal base layer results in thinner LED packaging. Compatibility with traditional die-mount techniques is also retained.
The company expects its devices to produce up to 6 cd at 20mW forward current. Production volumes are expected within the next year.
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.