Structural Characterization of HgTe/Cd/Te Superlattices

Abstract

Superlattices of HgTe and CdTe, grown on (100) and (111) CdTe, have been characterized by He ion backscattering spectrometry and x-ray double crystal diffractometry. Backscattering spectrometry gave basic information about the depth-distribution of layers, i.e. the number of layers in the superlattice, the thickness of CdTe overlayer and the location of damage in the underlying CdTe. Symmetric and asymmetric rocking curves gave information about crystal quality and layer thicknesses. Average strains in the directions perpendicular and parallel to the layer interfaces were obtained directly from the rocking curves. Strains and thicknesses of the HgTe and CdTe layers, as well as variations from layer to layer, were found by fitting the symmetric rocking curves with theoretical calculations based on a kinematic model for the diffraction. A tilt of the atomic planes in the epitaxial layers, relative to those in the substrate, was observed by means of rocking curves recorded from the same diffracting planes, but with reversed incident and diffracted beam directions.