Optical measurements of the surface plasmon of indium-tin oxide

The optical properties of indium-tin oxide are obtained by a least squares curve fit of the Drude intraband model to the attenuated total reflection spectra of its surface plasmon. The theoretical and experimental surface plasmon dispersion curves are analyzed on both, the real frequency axis and in the complex frequency plane. It is shown that a discrepancy exists between the damped theoretical dispersion curve and the attenuated total reflection dispersion curve unless the optical properties of indium-tin oxide are expressed as functions of complex frequency. The complex frequency dependent dielectric function of indium-tin oxide is analyzed and the effects of damping on both the dispersion relationship of the Drude free-electron model and the surface plasmon resonance frequency are determined. (author)