GaN-Based white-light-emitting diodes fabricated with a mixture of Ba3MgSi2O8:Eu2+ and Sr2SiO4:Eu2+ phosphors

The photoluminescence (PL) spectra of Ba3MgSi2O8:Eu2+ show one peak at 442 nm and two unresolved peaks at 505 rim. The 442 nm peak is attributed to the 4f-->5d transition of the Eu2+ ion doped in the Ba2+(I) site with a weak crystal field, while the 505 nm peak originates from Eu2+ ions on the Ba2+(II) or the Ba2+(III) site with a strong crystal field. The PL spectra of the SrSiO4:Eu2+ show two emission peaks at 470 nm and 560 nm. The emission intensity at 470 nm decreases with increasing Eu2+ concentration, while that at 560 nm increases. This can be understood by considering the energy transfer from the 470nm band to the 560nm band through multipolar interaction. The GaN-based white-light-emitting diode (LED) fabricated usima a mixture of Ba3MgSi2O8:Eu2+ and Sr2SiO4:Eu2+ phosphors has a broad-band spectrum, higher color renderinLy index and higher color stability against forward bias currents than Y3Al5O12:Ce3+-based white-LEDs.