Determination of the optical constants of a semiconductor thin film employing the matrix method

In the present work a formalism is developed based on the matrix method for the purpose of obtaining the values of the optical constants (n refractive index and k extinction coefficient) of thin film materials from the experimental reflectance (R) and transmittance (T) spectra. This formalism has been applied to the determination of the dependence on the wavelength (/spl lambda/) of n and k values in the visible range corresponding to a semiconductor (SnO/sub 2/) thin film deposited onto glass. The dependence on /spl lambda/ of the absorption coefficient (/spl alpha/) as well as the value of the energy gap has also been calculated. The nature of the optical transitions has also been ascertained. This technique has been found suitable for use as a student experiment.