Optical constants of evaporated gold films measured by surface plasmon resonance at telecommunication wavelengths

Abstract

We report the first measurement of the optical constants of evaporated gold films by using the surface plasmon resonance curve fitting method with an attenuated total reflection device from 16 to 70 nm thickness at telecommunication wavelengths. The results that were obtained by surface plasmon resonance measurement are in good agreement with those obtained by ellipsometry. Until now, optical constants of thin metal films are known to change according to the thickness due to the variation of the electrical resistivity. This phenomenon is also verified in this study by a simple surface plasmon resonance measurement. It is observed that for the gold films of thicknesses of less than 20 nm, the real part of the refractive index increases and the imaginary part decreases with decreasing film thickness. (c) 2008 American Institute of Physics.