Luminescence properties and energy transfer mechanism of Eu3+ and Tm3+ Co-doped AlN thin films

Eu3+, Tm3+ co-doped AlN thin films have been prepared through ion implantation for the first time. The implanted samples were annealed at 1180 °C in N2 to recover implantation damages and activate the rare-earth ions. Luminescence properties were investigated by photoluminescence and cathodoluminescence spectra. Under 325 nm laser excitation, for both Eu3+-doped AlN and Eu3+, Tm3+ co-doped AlN, the sharp characteristic emission lines corresponding to intra-4fn-shell transitions of Eu3+ were observed, but no any emission peak associated to Tm3+ ion was observed. According to the cathodoluminescence spectra, both Eu3+ and Tm3+ ions can be excited efficiently under high-energy electron beam. For Eu3+, Tm3+ co-doped AlN, the cathodoluminescence emission intensity of Eu3+ and Tm3+ ions varies with the dose ratio of these two ions. A possible energy transfer mechanism between Tm3+ and Eu3+ is proposed. Through changing the dose ratio of Eu3+ respect to Tm3+ ions, the chromaticity coordinates and color temperatures could be effectively regulated.