Low voltage electroluminescence of terbium- and thulium-doped zinc oxide films

Strong interest in developing technology for visual information stimulates research for thin film electroluminescent devices. Here, for the first time, we report that thulium- and terbium-doped zinc oxide films are suitable for electroluminescence applications. Two different devices were assembled as ITO/LiF/ZnO:RE/LiF/Al or ITO/SiO2/ZnO:RE/SiO2/Al, where ZnO:RE is a film of zinc oxide containing 10 at% of Tb3+ or Tm3+. Electroluminescence spectra show that besides a broad emission band with maximum around 650 nm assigned to ZnO, also emission lines from Tb3+ at 484 nm (5D4 → 7F6), 543 nm (5D4 → 7F5), and 589 nm (5D4 → 7F4), or from Tm3+ at 478 nm (1G4 → 3H6), and 511 nm (1D2 → 3H5) were detected. Intensity of emission as function of applied voltage and current–voltage characteristic are shown and discussed.