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 $Zn1−xCdxSe$ 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%.