In Situ Spectroscopic Ellipsometry of Rough Surfaces: Application to CdTe(211)B/Ge(211) Grown by Molecular-Beam Epitaxy

The surface morphology of the B-face of (211) cadmium telluride on germanium (211) is investigated by atomic force microscopy (AFM) and generalized ellipsometry (GE). It is apparent that one can obtain roughnesses on the order of two monolayers or less by manipulating the growth conditions. GE confirms that the surfaces are anisotropic. A model based on the Bruggeman effective-medium approximation is used to fit the data and yields values of the roughness that are in good agreement with those found by AFM. In situ data taken during growth are analyzed and a model for them is also proposed to analyze the formation of roughness and its evolution.