Zum optischen und elektrischen Verhalten der Metalle auf Grund von Messungen an sehr dünnen durch Aufdampfen erzeugten Schichten

Abstract

A theoretical treatment of the optical behaviour of thin metallic films with island structure was given in part (I) using a generalized Maxwell-Garnett formula. In this paper a more complete description is presented taking into account the dependence of the optical constants on particle size. Experimental data for particles below 20 Å can be fairly well expressed by calculated curves. The theory predicts, however, too sharp maxima in the spectral distribution of the absorption for larger particles. In order to achieve better agreement the area under the “bell” shaped absorption curves is used which is rather independent of the size and conductivity of the particles. The areas obtained compare well with experimental data. Thus it is possible by superposition of adjacent theoretical curves (belonging to different sites of the maxima) to take into account the inhomogenity of the experimental films and to get the correct magnitude of the maximum. The change in area with the position of the maximum is mainly caused by interband transitions which contribute to the dielectric constant also outside of the interband absorption range. It is improbable, however, that inhomogenity is the only reason for broadening. It is suggested that coupling between the microcircuits will also be important.

An attempt is made to get information on the temperature dependence of the effective mass by analysing the temperature dependence of the optical absorption.