Optical Properties of Metals: Au

Abstract

The dielectric function of Au films is determined ellipsometrically in the wave-number ranges 700 c m -l s v (= 1900 em-1 and 2500 cm-l 5 v 5 3000 cm-l as well as for 8900 cm-l v 5 5 32300 cm-l (1.1 eV 5 trw 5 4 eV). The spectra are discussed taking into account intra-and interband transitions. An energy-dependent plasma frequency and damping is found. The sample effects are essentially described within an effective medium approximation assuming the influence of voids. Some peculiarities of the frequency dependence of the damping parameter are likely due to the influence of fractals.Die dielektrische Funktion von Goldschichten wurde ellipsometrisch in den Wellenzahlgebieten 700 c m -1 5 Y 5 1900 cm-1 und 2500 cm-l 5 v 5 3000 cm-l sowie fur 8900 c m -l z v 5 5 32300 cm-1 (1,1 eV 5 hw < 4 eV) bestimmt. Die Spektren werden unter Berucksichtiguna von Inter-und Intraband-ubergiingen diskutiert. Es werden energieabhangige Plasmafrequenzen und Diimpfung gefunden. Die priparationsabhangigen Effekte kdnnen im wesentlichen n i t einer effektiven-Medium-NIherung beschrieben werden, wenn man die Existenz von kleinen Hohlraumen (voids) annimmt. Besonderheiten der Frequenzabhangigkeit der Dampfung sind vermutlich durch die Wirkung von Fraktalen zu erkliiren.

Ellipsometric Characterization of the Optical Constants of Metals: Thin Film versus Nanoparticle

“…The appropriate effective medium for wellisolated spherical particles in 3-D matrix is the simple Maxwell-Garnett model: (7) 3-D films were prepared by simultaneous sputtering of gold and PECVD of Si02• 14 The particle size was controlled by post-deposition annealing at 900°C. The effective dielectric function calculated from ellipsometric measurements is similar to the response of the discontinuous films shown in Figure 7.…”