... 415 Many materials have been studied; examples include: Dielectrics and optical coatings: Si3N4, Si 02, SiOJV,,, Al2O3, a-C:H, ZnO, Ti 02, ZnO/Ag/ZnOY TiOz/Ag/TiO2, Ago, In(Sn )20 3, and organic ... surface region of thickness t4). One of the films tl or t3 may consist of microscopic (less than 100 nm size) mixtures of two materials, such as SiO, and Si3N4. The volume ratios of these ... 2 D. E. Aspnes. In: Handbook of Optical Constana of Solid. (E. Palik, ed.) Academic Press, Orlando, 1985. Description of use of ellipsometry to determine optical constants of...