A prism coupler technique for characterizing thin film II-VI semiconductor systems

This article has two objectives. First, we determine the indices of refraction n of a series of molecular beam epitaxy-grown Zn_1-xCd_xSe epilayers using a technique based on coupling of evanescent waves via a prism into a semiconductor film. Highly precise values of n, and their dependence on the alloy composition x, are obtained for photon energies below the band gap of the alloy material. And second, we use these results to demonstrate the usefulness of the prism coupler method as a very reliable, convenient, and accurate tool for simultaneous determination of composition of semiconductor alloys in thin film form (since n depends on composition), and the film thickness. This method determines the film thickness with typical uncertainty of less than 0.5%.