2:30 PM - 2:45 PM
[14p-2K-4] Single Crystal Phosphors for High-Brightness White LEDs and LDs
Keywords:single crystal phosphor
White light-emitting diodes (WLEDs) are demanded for general lighting applications. The most economical WLED consists of a blue-LED and the yellow-phosphor Ce3+:Y3Al5O12 (Ce:YAG) ceramic powders. However, in applications that require high-brightness (HB), a conventional packaging possesses several drawbacks. That is why, a new concept of high-brightness white LEDs based on Ce:YAG single crystal phosphor plates (SCPPs), which can overcome the conventional temperature- and photo-degradation problems, is proposed. SCPPs demonstrated excellent thermal stability with no temperature quenching, high values of luminous efficacy and increased quantum efficiency. 2 inch Ce:YAG single crystals were grown with different compositions by standard Czochralski technique. SCPPs prepared by the grown single crystals exhibited a very high internal quantum efficiency (QEint) (over 95%), with an outstanding temperature stability in the temperature range 25-300oC. In contrast with powder and ceramic phosphors, we found that the Ce3+ emission of Ce:YAG SCPPs practically does not depend on the Ce concentration.