WAVELENGTH DEPENDENCES OF THE DIELECTRIC-CONSTANT OF THERMALLY EVAPORATED ALUMINUM FILMS

An in situ observation of the dielectric constant epsilon(m) of therma lly evaporated continuous aluminum (Al) thin films has been made in th e wavelength range 500-1000 nm by excitation of surface plasmon polari tons in the attenuated total reflection configuration. Such a dependen ce of the Al films fabricated in an ultrahigh vacuum environment has b een modeled with Ashcroft and Sturm's theory on an optical conductivit y, Fuchs and Sondheimer's theory and Mayadas and Shatzkes' theory on a n electrical conductivity of metal films. By analysing epsilon(m) as t he sum of an interband and Drude free-electron component, we have show n that electrons are scattered by a grain boundary and a surface. For oxide-contaminated films, the dielectric constant has been measured as a function of wavelength and the results have been interpreted by con sidering the epsilon(m) of films free from oxide contamination.