Parts | Days | Selection | Search | Downloads | Help
DS: Dünne Schichten
DS 23: Elektrische und optische Eigenschaften II
DS 23.8: Talk
Thursday, March 27, 2003, 17:00–17:15, GER/38
Optical properties of Eu doped yttria thin films — •Lutz Rabisch, Philipp Burmester, Takugo Ishii, and Günter Huber — Institut für Laser-Physik, Universität Hamburg, Jungiusstraße 9A, D-20355 Hamburg, Germany
Yttria (Y2O3) is an attractive host material for optically active rare-earth ions. In combination with α-Al2O3 an interesting, lattice matched epitaxial system arises which has a wide variety of possible applications (crystalline coatings, compact passive and active waveguides).
We demonstrate epitaxial growth of Eu:Y2O3 [111] films on Al2O3 (0001) substrates using the Electron Beam Evaporation (EBE)- and the Pulsed Laser Deposition (PLD) technique. Optical properties of the Eu:Y2O3-films were investigated by spectroscipic characterization of the 4f - 4f transitions of the Eu3+ ion. Depending on the fabrication process an amorphous interface between the substrate and the Y2O3 (crystalline) film can exist. The spectra of Eu-ions in such an interfacial amorphous layer are inhomogeniously broadened whereas the crystalline films show the same local symmetry of the Eu3+-centers as in a bulk crystal.
VUV and UV investigations reveal spectroscopic features arising at the Y2O3/Al2O3 interface. On the one hand excitonic states can be excited in the Eu:Y2O3-films at reduced energies in comparison to a bulk crystal, on the other hand a strong, spectrally broad luminescence that does not exist in the bulk material can be observed at λex = 205 nm. Both effects seem to be stronger in the PLD-films in comparison to the EBE-films. A model is presented, which explains this effect in terms of incorporated Eu2+ ions at the Y2O3/Al2O3 interface.