A detailed analysis of temperature dependence of optical constants of silver thin film measured by spectroscopic ellipsometry in the energy range 1.4 to 5 eV for temperatures ranging from 300 K to 650 K in steps of 50 K is presented in this paper. A microstructure modeling based on Bruggeman effective medium approximation is carried out on the temperature dependent optical constants. A red shift of ∼300 meV accompanied by a broadening of the interband transition is observed and an additional weak absorption edge emerges from the lower energy side of main interband absorption transition at 550 K. Drude model is applied to perform the analysis of dielectric function in the low energy region. The energy loss function −Im(1/ε) shows large damping with increasing temperature and this is a consequence of increasing magnitude of ε2 resulting from the composite transition in the region where ε1 is very small. These experimental results are corroborated with first principles electronic structure calculations using the full potential linearized augmented plane wave method within the frame-work of density functional theory.

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Thin films of nanocrystalline TiO2 were synthesized by spray pyrolysis technique in the temperature range 300 degrees C to 550 degrees C in steps of 50 degrees C. The films were coated on glass and quartz substrates by ultrasonic nebulization of titanium-oxy-acetyl acetonate followed by pyrolysis. The structure and morphology of the thin films were characterized by X-ray Diffraction (XRD), Raman Spectroscopy (RS) and Scanning Electron Microscopy (SEM), while the optical band gaps were measured by Spectroscopic Ellipsometry (SE) and UV-Visible spectroscopy. XRD investigations revealed distinct crystal structures of the films synthesized above and below 300 degrees C. While films grown at substrate temperature 300 degrees C were amorphous, those grown at 350 dgrees C and above showed tetragonal anatase crystal structure. The morphological investigations from SEM showed that the films deposited at 350 degrees C were porous and exhibited flower like morphology. The microstructures of the films grown on quartz at 450 degrees C were found to be uniform and dense. The nominal grain sizes evaluated from High Resolution SEM (HRSEM) studies were approximately 20 nm and compared well with the grain sizes calculated from XRD. The band gap values calculated from ellipsometry studies were approximately 3.7 eV and 3.95 eV for the films grown at 450 degrees C and 350 degrees C, respectively. This is in good agreement with those obtained from UV-Visible spectroscopy.

The temperature dependence of optical constants of titanium nitride thin film is investigated using Spectroscopic Ellipsometry (SE) between 1.4 and 5 eV in the temperature range of 300 K to 650 K in steps of 50 K. The real and imaginary parts of the dielectric functions ε1(E) and ε2(E) marginally increase with increase in temperature. A Drude Lorentz dielectric analysis based on free electron and oscillator model are carried out to describe the temperature behavior. With increase in temperature, the unscreened plasma frequency and broadening marginally decreased and increased, respectively. The parameters of the Lorentz oscillator model also showed that the relaxation time decreased with temperature while the oscillator energies increased. This study shows that owing to the marginal change in the refractive index with temperature, titanium nitride can be employed for surface plasmon sensor applications even in environments where rise in temperature is imminent.

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