Spectral  density analysis of thin gold films : Thickness and structure dependence of the optical properties

• In this paper we study the feasibility of representing the optical properties of ultrathin gold films by effective medium theories. Gold films with mass thicknesses in the range of 1.4 to 9.2 nm were deposited by DC magnetron sputtering onto non-heated glass substrates. Optical measurements in the range 0.25 to 2 µm were carried out by spectroscopic ellipsometry, and the effective complex dielectric function of each film was determined. The gold films were modelled as a mixture of gold and air, and a general effective medium description using the spectral density function (SDF) was used to describe their optical properties. Numerical inversion of the experimental dielectric function gave a broad and rather featureless SDF with a few superimposed peak structures, both for island structures and percolating films. The broad background is qualitatively similar to the predictions of the Bruggeman [Ann. Phys. (Leipzig), 5th series, 24 (1935) 636-679] model.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Keyword

Au thin films

ellipsometry

dielectric function

effective medium theory

spectral density function.

Engineering Science with specialization in Solid State Physics

Publication and Content Type

vet (subject category)

rec (subject category)