Effect of surface treatment upon luminous efficiency of YAG: Ce ceramics

For high-power white light-emitting diode devices (WLEDs), phosphor ceramics were widely used because of their high thermal conductivity and temperature resistance. In this study, Y2.998Al5O12: 0.002Ce(3+) ceramics were prepared via vacuum reaction sintering and treated by silicon carbide (SiC) abrasives with particle sizes of 8.6, 20, 25, 34, and 50 & mu;m to obtain a single textured surface. The transmittance, reflectance, luminous efficiency (LE) and photoluminescence (PL) intensity of the ceramics were investigated with various surface roughness and different placement. Compared with the double polished (DP) samples, the PL intensity and LE of the single-surface textured ceramics were greatly improved. It was shown that the roughest ceramics placed with the single polished (SP) side facing the direction of the excitation light (the SP-forward YAG: Ce ceramics) showed the best performance.