No abstract

SrAl 2 O 4 activated with Eu phosphors has been known to exhibit high brightness and long-lasting phosphorescence without radioactive materials. In this paper, SrAl 2 O 4 :Eu thin films have been successfully deposited on Si(100) or graphite substrates using an intense pulsed ion-beam evaporation technique. The results of X-ray diffraction and photoluminescence suggest that SrAl 2 O 4 :Eu thin films which have a polycrystalline structure can be produced in vacuum, without substrate heating and annealing. The composition and morphology of the films have been analyzed by Rutherford backscattering spectroscopy (RBS) and scanning electron microscopy (SEM). From RBS analysis, we have obtained good stoichiometry between the target and the films prepared.

SrAl2O4 activated with Eu, a long-phosphorescence material with high brightness, has been successfully deposited on Si substrates using intense pulsed ion-beam evaporation. Efficient preparation of long-phosphorescence thin films has been achieved using a high-density ablation plasma produced by the interaction of an intense pulsed ion-beam with the SrAl2O4:Eu target. The prepared SrAl2O4:Eu thin films had a polycrystalline structure without annealing and showed a typical photoluminescence of SrAl2O4:Eu at around 520 nm. Thermoluminescence (TL) measurements were carried out in order to obtain the lifetimes of the phosphorescence. In particular, TL spectra in the higher temperature region, which contributed to the long phosphorescence, were examined by the partial heating technique to evaluate the distributed trap depths and the lifetimes. The phosphorescence lifetime at 300 K for the prepared film was found to be about 180 min.