LAUSR

The excellent physical and chemical properties of aluminum oxynitride, Al(O)N, along with the tunable luminescence features of cerium ions (Ce) hold a promising future in white light sources based on chip technology. Manipulation of the emission color from blue to green, to yellow, and finally to white is demonstrated for the first time in Ce-doped Al(O)N thin films by tuning of the local structure, electronic structure, and film thickness. Analysis of the electronic structure by electron energy loss spectroscopy at the Ce-M4,5, Al-L2,3, O-K, and N-K edges and photoluminescence spectroscopies highlights the essential role of oxygen and postdeposition annealing in changing the valence state of Ce ions from Ce4+ (optically inactive) to Ce3+ (optically active) as well as the local field around Ce3+ and, finally, in activating excitation pathways through generation of specific defect complexes in the oxynitride matrix.