Effect of inhomogeneous broadening on time-resolved photoluminescence in CaAlSiN3: Eu2+

The decay behavior of CaAlSiN3:Eu2+ was monitored as a function of the detection wavelength on the Eu2+ emission band for various Eu2+ concentrations from 0.0005 to 0.05. The decay at the higher-energy side was faster and less linear than the lower-energy side decay for all Eu2+ concentrations. This was due to an inhomogeneous broadening induced by the random distribution of Al and Si ions at a crystallographic site in the CaAlSiN3 structure and to the successive site-to-site energy transfer. This phenomenon caused a redshift of the Eu2+ emission band as the Eu2+ concentration increased.