Packaging Technologies and Luminescence Properties of Ce:YAG Single Crystal for White Light-emitting Diode

The Ce:YAG single crystal for white light-emitting diode (WLED) application was grown by the Czochralski method. The thermal stability and optical properties of samples were characterized by absorption spectrum, photoluminescence spectra and temperature-dependent PL spectra. The photoelectric performance of WLEDs fabricated by the Ce:YAG single crystal were also measured. It is found that the Ce:YAG single crystal shows a broad emission band from 500 nm to 700 nm under blue light (wave length 466 nm). Absorption peaks, located at 202, 219, 247.3, 347.4 and 455.5 nm, are due to 4f->5d transition, and the energy of 5d orbits is divided into 21954, 29154, 40437, 45662 and 49505 cm super(-1). As the temperature increases, the PL intensity is reduced because of a higher energy of the super(2)F sub(7/2), and the damping upon PL intensity by the Ce:YAG single crystal (13.28%) are much lower than that by commercially available phosphors (30%). When the current is at a standard state and the luminous flux of emission