Growth of YAG:Ce~(3+)-Al_2O_3 eutectic ceramic by HDS method and its application for white LEDs

摘要

The resin-free YAG:Ce~(3+)-Al_2O_3 eutectic ceramic phosphor for white light emitting diodes (WLEDs) was successfully grown in vacuum by Horizontal Directional Solidification method (HDS). X-ray diffraction and scanning electron microscopy indicate that this material has a typical eutectic structure of interpenetrating sapphire and garnet phases. The excitation spectra, emission spectra and temperature characteristics of the eutectic show that it is characterized by a wide excitation band and it has good stability in high temperature. In X-ray photoelectron spectroscopy, annealing in an air atmosphere could eliminate the oxygen vacancies and didn't change the Ce~(3+) valence in the eutectic. The YAG:Ce~(3+)-Al_2O_3 eutectic ceramic with different thickness was fixed in COB (chip on board) element for researching the performance of the WLEDs with the phosphor. The electroluminescence characterization of the WLEDs show that the WLEDs with the eutectic ceramic are more excellent than the common commercial WLEDs.