Misfit relaxation behavior in CdHgTe layers grown by molecular beam epitaxy on CdZnTe substrates

Uniform layers of cadmium mercury telluride have been grown on inhomogeneous cadmium zinc telluride substrates by molecular beam epitaxy so that a single epitaxial layer experiences a laterally varying lattice mismatch. The lateral variations of layer and substrate lattice parameters, layer lattice tilt, diffraction peak width, etch pit density (EPD) and surface crosshatch have been characterized, and all measured quantities are reported as functions of the substrate lattice parameter. At small mismatch, the layer appears to be elastically deformed. Beyond a certain critical mismatch, the onset of relaxation is clearly observed in the layer lattice parameter. Relaxation leads to appearance of surface crosshatch and an increased diffraction peak width, but a reduction in EPD, suggesting a reduction in the density of threading dislocations within the layer.