Variable angle of incidence spectroscopic ellipsometry: Application to GaAs-Al<i>x</i>Ga1−<i>x</i>As multiple heterostructures

Abstract

The sensitivity of spectroscopic ellipsometry data to multilayer model parameters is shown to be a strong function of the angle of incidence. A quantitative study of sensitivity versus angle of incidence is performed for a GaAs-AlxGa1−xAs-GaAs substrate structure, showing that maximum sensitivity to layer thicknesses and AlGaAs composition occurs near the wavelength-dependent principal angle. These results are verified by experimental measurements on two molecular-beam epitaxy grown samples. New spectral features, not found in previous ellipsometry studies of similar structures, are also reported.