A NEW METHOD FOR THE DETERMINATION OF THE THICKNESS, THE OPTICAL-CONSTANTS AND THE RELAXATION-TIME OF WEAKLY ABSORBING SEMICONDUCTING THIN-FILMS

A new method for the complete optical analysis of weakly absorbing semiconductive thin films is presented. The thickness d, the two optical constants n and k, and the spectral dependence of the free carriers relaxation time are determined directly by using only the envelopes of the reflectance extrema. The rigorous equations relating the reflectance R( omega ) to n and k have been solved and explicit expressions for n and k in terms of R( omega ) are given. The approximate formulae are in closed form and the simple straightforward calculations can be made using a programmable pocket calculator. The accuracy of the method, better than 1% for n and d, is of the same order or even better than the accuracy of the more elaborate iteration methods.