A Method For The Determination Of The Complex Refractive Index Of Non-metallic Thin Films Using Photometric Measurements At Normal Incidence

A method is proposed for the determination of the complex refractive index of non-metallic thin films using photometric measurements at normal incidence over an extended wavelength interval. A necessary condition for the applicability of the method is the existence of maxima and minima in the reflectance due to interference effects. The problem of multiple solutions is analysed and the optical thicknesses at the extrema are used for choosing the correct solutions. For absorbing films two alternative procedures are described. One procedure requires an approximate value of the film thickness to start with and refines it during the calculation. The other procedure does not depend on a previous knowledge of the thickness but gives it as a result together with n(λ) and k(λ). A separate procedure is proposed for transparent and almost transparent films. An application of the method is carried out in which excellent agreement is obtained between calculated and experimental results. © 1983.1002155168Heavens, (1964) Phys. Thin Films, 2, pp. 193-238Abelès, Optical Properties of Metallic Films (1971) Phys. Thin Films, 6, pp. 151-204Malé, (1950) C.R. Acad. Sci., 230, p. 1349Malé, (1954) Ann. Phys. (Paris), 9, p. 10Malé, Détermination simultanée des indices et de l'épaisseur des couches minces absorbantes (1964) Journal de Physique, 25, p. 74Hall, Jr., Ferguson, Optical Properties of Cadmium Sulfide and Zinc Sulfide from 06 Micron to 14 Microns (1955) Journal of the Optical Society of America, 45, p. 714Goodman, (1978) Appl. Opt., 17, p. 2779Nilsson, Determination of Optical Constants from Intensity Measurements at Normal Incidence (1968) Applied Optics, 7, p. 435Abelès, Thèye, Méthode de calcul des constantes optiques des couches minces absorbantes à partir de mesures de réflexion et de transmission (1966) Surface Science, 5, p. 325Denton, Campbell, Tomlin, (1972) J. Phys. D, 5, p. 852Ward, Nag, Dixon, (1969) J. Phys. D, 2, p. 301Ward, Nag, (1970) J. Phys. D, 3, p. 462Cook, Christy, (1980) J. Appl. Phys., 51, p. 668Carey, Thomas, Newman, (1980) Thin Solid Films, 66, p. 139Born, Wolf, (1975) Principles of Optics, pp. 61-66. , 5th edn., Pergamon, New YorkBorn, Wolf, (1975) Principles of Optics, pp. 628-632. , 5th edn., Pergamon, New YorkKnittl, (1976) Optics of Thin Films, pp. 480-484. , Wiley, New YorkBringans, (1977) J. Phys. D, 10, p. 1855Bennet, Booty, Computational Method for Determining n and k for a Thin Film from the Measured Reflectance, Transmittance, and Film Thickness (1966) Applied Optics, 5, p. 4