Luminescence yield in Al and Tb~(3+)delta-doped oxide thin films fabricated by electron beam evaporation

摘要

Electron beam evaporation was employed in order to fabricate Al- and Tb-codoped Si oxide multilayers via the delta-doping approach. This methodology permits the control of the rare-earth (RE) separation along the growth direction with nanometric resolution. To investigate the control of the RE separation in the growth direction, different SiO_2 thicknesses were studied. After deposition, the samples were submitted to different annealing processes for 1 h in N_2, at temperatures ranging from 700 to 1100 ℃. Photoluminescence experiments reveal narrow emissions ascribed to Tb~(3+) ions in all samples, with an intensity variation depending on the oxide thickness and annealing temperature. In addition, the incorporation of Al under different spatial configurations produced an enhancement of more than one order of magnitude in the photoluminescence intensity, in respect to the best sample without Al. Finally, time-resolved measurements were carried out in order to determine the ~5D_4→~7F_5 transition dynamics, obtaining a decay time of ～1.6 ms ascribed to the Tb~(3+) ions.