Color tunable Ca0.96Eu0.04Al2-xSixO4-xNx phosphors are prepared using a convenient solid-state reaction. Si-N content (x) was adjusted to study its effect on luminescence and thermal stability. This incorporation of Si-N effect drastically changes the bonds of phosphor materials from being ionic-rich to being covalent-rich. This transformation is investigated using x-ray diffraction, x-ray photoelectron spectra, and photoluminescence measurements. When the Si-N content was increased to 2, the phosphor properties significantly improved, with a broad excitation band, tunable-emission, and a high thermal quenching temperature (T-50 > 175 > C). Results show that Ca0.96Eu0.04Si2O2N2 green phosphors with a broad excitation band and good thermal stability have potential for use in solid-state lighting and solar cells. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3551528] All rights reserved. A