Investigation of temperature dependent dielectric constant of a sputtered TiN thin film by spectroscopic ellipsometry.

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 300K to 650K in steps of 50K. 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. [ABSTRACT FROM AUTHOR]