Fluorescence Properties of Sol-gel Derived Er3+-doped TiO2-Al2O3 Composite Thin Films

Abstract

The photoluminescence (PL) emission from the first excited state (4I13/2) to the ground state (4I15/2) in Er3+ occurs at the wavelength 1.54 µ m, a standard telecommunication wavelength of silica-based optical fibers. Both PL intensity and FWHM spectral width will increase with more Er3+ doping. In the present study, the sol-gel spin coating process was used to prepare the Er3+-doped TiO2-Al2O3 composite thin films. With increasing Al2O3 content, the phase transformation of amorphous to anatase states was delayed in the composite films. The incorporation of Er3+ ions reduces the amount of aluminum sites in the 4-fold coordination and increases the 5-fold coordination. Furthermore, it was found that the PL intensity could be enhanced with the increasing of Al2O3 addition in the Er+3-doped TiO2-Al2O3 composite films.