Ce-doped Al2O3−YAG eutectic and its application for white LEDs

• Ce doped Al2O3−YAG eutectic has been successfully grown by the Czochralski method.
• The eutectic has a higher segregation coefficient of Ce3+ than YAG single crystal.
• Photoluminescence properties of Ce-doped Al2O3–YAG eutectic were investigated.
• Various white colours could be obtained as required, by varying the eutectic phosphor thickness.
• The distinctive structure of eutectic made it have a better performance in LED than particle-dispersed system.

Ce-doped Al2O3−YAG (Y3Al5O12, yttrium aluminum garnet) eutectic, a resin-free phosphor for white light emitting diodes (WLEDs), was successfully grown by the Czochralski method. X-ray diffraction and scanning electron microscopy show that this material has a typical eutectic structure of interpenetrating sapphire and garnet phases, as well as lamellar spacing in the order of tens of microns. The eutectic has a higher Ce3+ segregation coefficient than YAG single crystal. The photoluminescence properties of this eutectic were also investigated. Results show that it is characterized by a wide excitation band, and that the luminous efficiency of a eutectic-packaged LED is higher than that of a phosphor powder-packaged LED. The findings indicate that the Al2O3−YAG eutectic is a promising phosphor for WLED applications.