Preparation of Nb-doped Anatase Type TiO₂ Epitaxial Thin Films and Excitation of Surface Plasmon Polaritons

抄録

We have fabricated highly crystallized thin films of niobium-doped anatase type titania (Ti_1−xNb_xO₂) to examine the relationship between the electronic transport properties and the plasmonic response. Ti_1−xNb_xO₂ thin films were epitaxially grown on LaTiO₃ substrates by using pulsed laser deposition. Attenuated total reflectance spectra in the infrared (IR) region measured using the Otto configuration show a dip for p-polarized light, corresponding to an excitation of surface plasmon polaritons. The IR reflectivity data can be well reproduced by the theoretical calculation based on the Fresnel model, in which the dielectric function of Ti_1−xNb_xO₂ can be modeled by the combination of a Lorentz term and a Drude term. The real part of dielectric function for Ti_1−xNb_xO₂ (x = 0.03) is negative at the wavelengths longer than 2.78 μm in the IR region.