White Led Lighting Devices Technology Research

The LEDs began to penetrate into lighting source after the first white LED was born in 1998, It was forecasted that the LED will be third generation lighting after incandescent and fluorescent bulbs. Like inorganic semiconductor transittors, which displaced vacuum tubes for computation, solid-state lighting of LED is a disruptive technology that has the potential to displace vacuum or gas tubes (like those used in traditional incandescent or fluorescent lamps) for lighting. In this paper, I mainly discuss technology about phosphor-converted white LEDs and relative device. The main results as following :1, Two phosphors for phosphor-converted white LEDs was investigated and fabricated. One is (Y3-x-yGdy) (Al5-zGaz) O12: Ce3+, the other is CaS : Eu2+.zz2, The first white LEDs in china was fabricated with (Y3-x-yGdy)(Al5-zGaz)O12: Ce3+. The luminescent intensity is 2890 mcd, the color rendering index is 81, the chromaticity coordinate is x=0. 29, y=0. 33. The results of the color rendering index and the chromaticity coordinat is better than that of foreign productive levels in 2001.3, The first integrated LED lamp was fabricated in china. The power of integrated LED lamp is 5 Watt; the luminous efficiency is 12. 6 Lm/W; the color rendering index is 80. 6; the chromaticity coordinate is ;c=0. 292, y=0. 313. These results were better than the technology performance targets of SSL-LED n which will be reach in 2007.4, The useful life for GaN-based blue LED with Al2O3 and SiC substrate was studied. The short useful life reasons of LED with Al2O3 substrate is that the current density is too large in GaN-buffer and n-GaN layers. The useful life curves of GaN-based blue LED with Al2O3 and SiC substrate is fit single exponential function [I=I1+I2exp(-t/ )]. Fron this function, we could get aging information of LED about stable inteneity 1, decay intensity I2 and decay time . The novel method of evaluating aging properties of LEDs was put forward.5, These technology were used in the national defence and economy.