Thin Solid Films, Vol.520, No.1, 131-137, 2011
Structural and optical properties of tellurite thin film glasses deposited by pulsed laser deposition
Tellurite (TeO(2)-TiO(2)-Nb(2)O(5)) thin film glasses have been produced by pulsed laser deposition at room temperature at laser energy densities in the range of 0.8-1.5 J/cm(2) and oxygen pressures in the range of 3-11 Pa. The oxygen concentration in the films increases with laser energy density to reach values very close to that of the bulk glass at 1.5 J/cm(2), while films prepared at 1.5 J/cm2 and pressures above <= 5 Pa show oxygen concentration in excess of 10% comparing to the glass. X-ray photoelectron spectroscopy shows the presence of elementary Te in films deposited at O(2) pressures Pa that is not detected at higher pressures, while analysis of Raman spectra of the samples suggests a progressive substitution of TeO(3) trigonal pyramids by Teat trigonal bipyramids in the films when increasing their oxygen content. Spectroscopic ellipsometry analysis combined with Cauchy and effective medium modeling demonstrates the influence of these compositional and structural modifications on the optical response of the films. Since the oxygen content determines their optical response through the structural modifications induced in the films, those can be effectively controlled by tuning the deposition conditions, and films having large n (2.08) and reduced k (< 10(-4)) at 1.5 mu m have been produced using the optimum deposition conditions. (C) 2011 Elsevier B.V All rights reserved.
Keywords:Tellurite glasses;Thin films;Pulsed laser deposition;Raman spectroscopy;X-ray Photoelectron Spectroscopy;Optical properties