DETERMINATION OF THE OPTICAL-PROPERTIES OF THIN-FILMS

The simultaneous determination of the refractive index, absorption coefficient and thickness of thin-films in an unambiguous manner has been the subject of many research teams. Reported results show a strong dependence on the method [1]. In this work, we give an account of the methods we have developed for optical characterization of thin-films, based on external [2] and internal reflectometry [3], including the excitation and detection of surface electromagnetic waves (surface plasmons) in the case of metals and two characteristic isoreflectance angles in the case of weak absorbing and transparent films. In all cases, the samples are prepared with dielectric stepped overcoating protecting the sample degradation when exposed to ambient; these treatments give unambiguous information on the optical properties and thickness of the sample. Some examples on dielectric, weak absorbing and metallic film are given.