Reflection of Light by a System of Nonabsorbing Isotropic Film–Nonabsorbing Isotropic Substrate with Randomly Rough Boundaries

The reflection of light by a system consisting of a nonabsorbing isotropic film and nonabsorbing isotropic substrate with both boundaries (air–film and film–substrate) rough is considered. The scalar theory of light scattering on such a system has been developed. The formulas characterizing both the coherent and the incoherent components of the reflected-light flux have been derived for the case of the identical film (both boundaries are rough, the air–film boundary is a copy of the film–substrate boundary) as well as for the general film (both boundaries are rough and different). The numerical results of the calculation performed for a system of SiO2–Si are presented and the experimental results for the case of art identical film of SiO2 on a Si single crystal are given. The agreement between the theory and the experiment is fairly good. The correctness of the film thickness and its index of refraction depends to a fairly high degree on the roughness of the air–film and film–substrate boundaries.