Cree's blue LED has quantum efficiency of 35%
White LEDs fabricated using these novel XBright chips produced 4.1 lumens of light in industry-standard LED packages with an electrical energy conversion efficiency of 65 lumens per watt (lm/W) at 20 mA.
In laboratory packages, the XBright chips produced 4.7 lumens of light with 74 lumens per watt.
According to Cree, these are the highest known efficiencies publicly reported for LEDs emitting in the blue and white wavelength spectrum.
The work was sponsored, in part, by the Department of Energy’s Office of Energy Efficiency and Renewable Energy, as well as by the State of California’s California Technology Investment Partnership.
XThin LEDs
Cree has also unveiled its latest product line, the XThin series of InGaN-on-SiC LEDs.
The vertically structured LED chips are approximately 115 microns in height, representing over a 50% reduction in the typical height of Cree’s LEDs.
The XThin devices have a lower forward voltage than Cree’s standard XBright products. XBright chips are geometrically shaped and mounted with the epitaxial layer side down, in order to maximize light extraction efficiency for improved white light conversion.
In July 2003, Cree introduced RazerThin LEDs with a typical height of 95 microns (see Cree commences production of RazerThin LEDs). The RazerThin LEDs are not shaped.
“We are excited to introduce our newest LED product with a lower forward voltage and a new thinner design which will enhance our XBright family of products,” said Mike Dunn, VP of Optoelectronics.
“We believe that as we continue to add improvements to our chips, it will enable new opportunities in the marketplace for our LED products.”
Target applications for this product include white LEDs for use as LCD backlights and digital camera flashes in next generation mobile appliances where brightness, sub-miniaturization, and low power consumption are required.
