Red, green, and blue luminescence from ZnGa₂O₄ nanowire arrays

Large-area (>1 cm²), vertically aligned ZnGa₂O₄, Mn²⁺-doped ZnGa₂O₄ (ZnGa₂O₄:Mn²⁺) and Cr³⁺-doped ZnGa₂O₄ (ZnGa₂O₄:Cr³⁺) nanowire arrays were synthesized by a two-step thermal evaporation method using ZnO nanowire arrays as the templates followed by reaction with Ga and/or dopant (Mn or Cr) vapors. Bright red, green, and blue luminescence was achieved, respectively, from ZnGa₂O₄:Cr³⁺, ZnGa₂O₄:Mn²⁺, and ZnGa₂O₄ nanowire arrays under ultra-violet light irradiation. The realization of three primary colors from one host material suggests that full color display based on ZnGa₂O₄ nanowires might be achievable.