Über optische Konstanten, elektrischen Widerstand und Struktur dünner Metallschichten

Abstract

537 Ub e r opt4sche E o n s t ant en, e Zektr6schm W d d erst an d zcnd S t m k t u r d i h n w MetaZEsch4chtenn)Von Josef E r a z c t k r U m e r

Dimensional effects in thin gold films

“…Calculation using traditional formulae leads to a hardly apprehensible abrupt increase of refraction index with the layer thickness decreasing. This very dependence was deduced by three different authors for thin gold films [2][3][4], as well as in papers [5][6][7] for atomic semicon- ductors. Because with d decreasing to zero, films acquire a two-dimensional hel structure, substance density in which is much lower than the one of a bulk sample, a qualitatively contrary thickness dependence of n should be expected.…”

“…It may be this very substitution that leads to results which cause surprise. For example, with the reducing thickness of thin gold films [2][3][4] (Fig. 1) and atomic semiconductors [5][6][7], the refraction coefficient grows unlimitedly.…”

Optical properties of thin metal films

“…It is this change that leads to meaningless results. For example, when a thickness of metal [13][14][15] and semiconductor [16][17][18] films tends to zero value, the refraction index increases to infinity, though it must approach to unity. Such monotonic thickness dependence of the refraction in-dex for thin absorbing films all the more cast doubt, because it must have at least one resonance maximum on the curve n = f (d) that corresponds to a wedgeshaped layer thickness of which changes from zero to the value when this layer becomes absolutely transparent.…”

Flexible Transparent Metal/Polymer Composite Materials Based on Optical Resonant Laminate Structures

“…To the authors' knowledge, the first experimental studies on the effect of film thickness on the optical constants of metals are due to Krautkramer and co-workers as well as Maléand coworkers who systematically evaluated the effect of film thickness on the optical constants of thin films of gold and silver. 27,28 A compilation of studies on the optical properties of thin metal films is provided in more recent reviews by Heavens. 29,30 The conclusion of these previous studies is that a significant reduction of the films' (complex) refractive index is expected for film thicknesses below 20 nm in the case of Au (and similarly for other metals such as Ag, Cu, Pt, and Pd).…”

“…In contrast to spherical systems, little information is available regarding the effect of spatial confinement on the optical constants in thin metal films. To the authors’ knowledge, the first experimental studies on the effect of film thickness on the optical constants of metals are due to Krautkrämer and co-workers as well as Malé and co-workers who systematically evaluated the effect of film thickness on the optical constants of thin films of gold and silver. , A compilation of studies on the optical properties of thin metal films is provided in more recent reviews by Heavens. , The conclusion of these previous studies is that a significant reduction of the films’ (complex) refractive index is expected for film thicknesses below 20 nm in the case of Au (and similarly for other metals such as Ag, Cu, Pt, and Pd). Since for the present (Au 10 |PS 140 ) 4 system, the thickness of the gold layers is significantly below the electron mean free path (and since for 10 nm layer thickness no experimental data is available in the wavelength range of interest), the optical constants n and k were determined experimentally to facilitate proper modeling of the films’ optical response.…”