Sintering YAG:Ce phosphor ceramic layers onto glass substrates by CO2 laser for WLED applications

Abstract

Cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor layers were sintered onto glass using CO2 laser. The layer adhesion was found to depend on the spin coating thickness. The x-ray diffraction indicated the formation of YAG phase, with minor impurities of Y2SiO5 and Y4Al2O9. When the coating thickness was 65 μm, the laser beam reacted thoroughly with glass and YAG precursors, and a liquid phase was formed, producing a thin amorphous layer (∼5 μm) on the surface grooves. However, when the thickness was increased to 170 μm, the laser beam could not penetrate to react entirely with YAG precursors, resulting in more raw residues and poor adhesion. The sintered YAG:Ce phosphor layers on glass were characterized via photoluminescence, presenting yellow emission with a thermal quench to 75% at 125 °C, which is comparable to that of the solid-state reacted YAG:Ce ceramics.