Photoluminescence of TiO2: Eu3+ thin films obtained by sol-gel on Si and Corning glass substrates

Abstract

In this paper we report results on the fabrication and characterisation of thin films of titania (TiO2), a novel host for the Eu3+ activator ion. The titania films were produced by the sol-gel process at room temperature using the dip coating method and deposited on silicon and corning glass substrates. It is shown that different surface morphology and crystalline structures are developed for the TiO2:Eu films deposited on different substrates. When an above TiO2 band gap photoexcitation line (He-Cd 325 nm) is used, the films show a strong red photoluminescence (PL) signal associated with the D-5(0) --> F-7(1) transition of the electronic structure of Eu3+. The PL emission has better characteristics for those films deposited on silicon wafers. The PL signal become,, weaker after annealing at relatively low temperatures such as 450 degreesC due to thickness reduction of the TiO2 film and the loss of Eu in the near-surface region. (C) 2001 Elsevier Science B.V. All rights reserved.