Determination of the optical constants (n, k) of thin dielectric films

A method for the determination of the optical constants and the thickness of thin dielectric films on transparent substrates is proposed. It requires measurements at normal incidence of the transmission from two films of different thicknesses. The derivation is complicated by the existence of multiple solutions of the relevant equations. A procedure is given for determining the correct solutions for the indices of refraction and absorption and also for accurately fixing the thickness of the films. Advantages of the present method over existing methods are better accuracy and readily available measurement facilities. The method has been applied successfully to films of titanium oxide.