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/SiO 2/ZnO:RE/SiO 2/Al, where ZnO:RE is a film of zinc oxide containing 10 at% of Tb 3+ or Tm 3+. Electroluminescence spectra show that besides a broad emission band with maximum around 650 nm assigned to ZnO, also emission lines from Tb 3+ at 484 nm ( 5D 4 → 7F 6), 543 nm ( 5D 4 → 7F 5), and 589 nm ( 5D 4 → 7F 4), or from Tm 3+ at 478 nm ( 1G 4 → 3H 6), and 511 nm ( 1D 2 → 3H 5) were detected. Intensity of emission as function of applied voltage and current–voltage characteristic are shown and discussed.