Cree Japan, backed by Cree Inc, has recently launched a white LED lamp "XLamp XB-D”, at the 4th LED/OLED Lighting Technology Expo in Tokyo.

The company employed a newly-developed LED chip "DA Chip Family" which was developed by improving the light extraction efficiency of a blue LED chip, to realize the small size and higher brightness. It improved the light extraction efficiency by forming several V-shaped ditches on the substrate of the blue LED chip.

The DA Chip is made by growing gallium nitride (GaN)-based semiconductor single crystals, which will become a light-emitting layer, on a silicon carbide (SiC) substrate and forming V-shaped ditches from the outside of the SiC substrate. Light is extracted from the side having the V-shaped ditches.

The LED lamp has benefited a lot from the new chip. The footprint of the package is 2.45 x 2.45mm, half that of the former product (3.45 x 3.45mm). With an input current of 350mA, the luminous flux of the lamp is 148lm (when the junction temperature is 25°C), higher than that of the former product (139lm).  Even when the junction temperature is 85°C, which is a normal temperature of an LED lighting apparatus in use, the luminous flux of the lamp is about 130lm. Cree started to ship the product in January 2012.

It’s noted that Cree Japan showed a road map of the luminous efficiencies of its white LEDs. According to the road map, Cree will achieve a luminous efficiency of 231lm/W in 2011 or 2012 in the R&D level and commercialize a white LED having an equivalent efficiency in 2014. About one year ago, Cree Japan announced that it would develop and commercialize products with efficiencies up to 208lm/W in a road map.