Oriol announces new vertical GaN HB-LED production process
Vertical devices save space as they require only a single wirebond, using the bottom of the chip as the second electrical contact, thereby flowing current vertically through the device. Vertical devices have previously been limited to GaN grown on SiC substrates, though conductive, SiC is opaque, and absorbs a substantial portion of the light being emitted.
Sapphire substrates are less expensive, making them a popular choice for GaN growth. However, sapphire is insulating and LEDs on sapphire require two wirebonds on top of each chip. With the electrical current traveling laterally between these two contacts the packaging efficiency is greatly reduced. While sapphire is transparent, enabling more light to escape from the chip, it unfortunately acts as a thermal insulator that traps heat, dramatically reducing the high operating current efficiency and ultimately limiting the available applications.
Oriol has combined the best of both worlds by using sapphire as the initial GaN growth substrate then bonding a thermally and electrically conductive metal layer on top of the GaN. By employing a proprietary lift-off technique, the GaN LED structure is removed from the sapphire substrate, leaving the GaN and the reflective base ready for the fabrication of vertical devices.
The resulting vertical device bonded to a reflective metal layer exhibits low thermal resistance and high electrical conductivity, lending itself to thinner LED packaging while remaining rugged enough to retain compatibility with traditional die-mount techniques. The performance of Oriol s initial blue spectrum product line, when packaged, is projected to produce up to 6 candela at 20 mA forward current, when using 5 mm, 15 degree viewing angle packaging.
"This vertical device truly differentiates Oriol from all other HB-LED chip makers," said Oriol s President, G. Lancaster. "Customers will finally be able to break away from the previous choice between silicon carbide and sapphire-based devices which either require special handling or are limited in their performance."
Engineering samples of the vertical Gigabright chip will be available within three months and production volumes are projected to ramp-up early in the 4th quarter.
Tom Jory
Tel. +1 408-327-9940 x225
E-mail: tom@oriolinc.com
Web site: http://www.oriolinc.com
