Abstract We investigated the luminescence properties of (Ca 1− x Zn x )Ga 2S 4:Eu 2+ phosphor as a function of Zn 2+ and Eu 2+ concentrations. The luminescence intensity was markedly enhanced by increasing the mole fraction of Zn 2+ at Ca 2+ sites. Lacking any Zn 2+ ions, CaGa 2S 4:0.01Eu 2+ converted only 18.1% of the absorbed blue light into luminescence. As the Zn 2+ concentration increased, the quantum yield increased and reached a maximum of 24.4% at x = 0.1. Furthermore, to fabricate the device, the optimized green-yellow (Ca 0.9Zn 0.1)Ga 2S 4:Eu 2+ phosphor was coated with MgO. White light was generated by combining the MgO-coated phosphor and the blue emission from a GaN chip.