Optical properties of Au-SiO2 composite films - a possible candidate as anelement in phase-change optical media

The thin films used for phase-change recording media need to be chosen in c onsideration of both optical and thermal properties. Metal-dielectric compo site films are one of the candidates for such films; they may allow adjustm ent of the light absorption and hear flow inside the recording medium. The properties of Au-SiO2 composite films are examined by comparing experimenta l results with theoretical predictions obtained using the Maxwell-Garnett t heory. It is found that the optical constant for a sputter-deposited Au-SiO 2 composite film cannot be accurately predicted by the theory for wavelengt hs longer than 500 nm if an assumed value of the optical constant of the bu lk metal is used. However. much more accurate predictions are performed if the optical constant of the metal particles is used. It is shown that appro priate values for the optical constant of the metal particles are the ones calculated by the inverse application of the,Maxwell Garnett theory.