A phosphor-free white light source, where an indium-containing light-emitting layer, as well as subsequent device layers, is deposited on a textured surface.
Typical incandescent light sources, while highly energy-inefficient, have a desirable characteristic broad-emission spectrum and a high color-rendering index. In order to mimic these latter attributes in gallium nitride (GaN) based devices, current state-of-the-art designs have certain disadvantages. The process of down-conversion is inherently inefficient due to the Stokes shift and poor conversion efficiency. The emission spectrum and intensity are highly sensitive to spatial variations in the phosphor composition and thickness, and may vary greatly with emission direction. Finally, while the diode itself may have a long lifetime, phosphors typically degrade with time, resulting in a variation of the emission spectrum with time. Current designs proposing methods to obtain "white" light without the aid of phosphors typically rely on a high-indium content layer deposited under conditions that result in poor material quality.
Researchers at the University of California, Santa Barbara have developed a phosphor-free white light source, where an indium-containing light-emitting layer, as well as subsequent device layers, is deposited on a textured surface. It is possible to develop a device with suitably textured areas that would emit at two or more peak wavelengths, where both peak emission wavelengths are produced primarily from the indium-containing light-emitting layer.
This technology is available for licensing.
|United States Of America||Issued Patent||8,643,036||02/04/2014||2004-208|
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