Infra-red emission properties of ZnO:Er thin films prepared on the sapphire substrates

ZnO thin films with various Er content were deposited on c-plane sapphire substrates by rf magnetron sputtering. As deposited-films showed poor crystallinity due to the strains induced in the films, but the well-developed (0 0 2) preferred films could be achieved after post-annealing under air atmosphere. X-ray diffraction patterns of 5 and 10 mol% Er2O3 doped ZnO films exhibited the un-reacted Er2O3 phase, which were possibly located at the grain boundaries. The emission spectra of ZnO:Er films pumped by 515 nm laser showed infrared emissions at 1.538 μm due to the energy transition between 4I13/2 and 4I15/2 of Eu3+ ions. IR emission behaviors strongly correlated with the film structure.