Local analysis of Eu emission in CaAlSiN.

We have investigated the local luminescence properties of Eu-doped CaAlSiN by using low-energy electron beam (e-beam) techniques. The particles yield broad emission centered at 655 nm with a shoulder at higher wavelength under light excitation, and a broad band around 643 nm with a tail at 540 nm under e-beam excitation. Using cathodoluminescence (CL) in a scanning electron microscope (SEM), we have observed small and large particles, which, although with different compositions, exhibit Eu-related emissions at 645 and 635 nm, respectively. Local CL measurements reveal that the Eu emission may actually consist of several bands. In addition to the red broad band, regularly spaced sharp peaks have been occasionally observed. These luminescence variations may originate from a variation in the composition inside CaAlSiN.