The effect of annealing temperature on the structural and optical properties of sputtered niobium-oxide films has been investigated. The temperature dependence of structure, density, and optical constants has been studied by Rutherford backscattering, x-ray diffraction, x-ray reflection, optical spectroscopy, and variable angle spectroscopic ellipsometry techniques. Rutherford backscattering measurements show no variation in the stoichiometry of the films upon annealing of amorphous Nb_(2)O_(5) films, while amorphous NbO is oxidized to Nb_(2)O_(5). X-ray diffraction studies show that as-deposited films are amorphous and only crystallize at around 500℃. X-ray reflectivity studies reveal a continuous increase of film density with increasing annealing temperature. Optical spectroscopy and spectroscopic ellipsometry confirm that the refractive index n and the band gap E_(g) increase upon increasing annealing temperature. The variation of the refractive index with density of the niobium-oxide films is observed to follow the Clausius-Mossotti relation and the molecular electronic polarizability has been deduced from the straight line fit of Lorentz-Lorentz law.
展开▼
