Ellipsometric study of Si0.5Ge0.5/Si strained-layer superlattices

Abstract
We present an ellipsometric study of two Si0.5Ge0.5/Si strained‐layer superlattices grown by MBE at low temperature (500 °C), and compare our results with x‐ray diffraction (XRD) estimates. Excellent agreement is obtained between target values, XRD, and ellipsometry when one of two available SixGe1−x databases is used. We show that ellipsometry can be used to nondestructively determine the number of superlattice periods, layer thicknesses, SixGe1−x composition, and oxide thickness without resorting to additional sources of information. We also note that we do not observe any strain effect on the E1 critical point.