Elastic and plastic deformation in low mismatched

Abstract

We have measured, by X-ray diffraction, the deformation of uniform cadmium mercury telluride layers epitaxially grown on cadmium zinc telluride substrates with varying zinc concentration. It is then possible, within the same sample, to clearly identify elastic deformation in the regions of small lattice mismatch and plastic deformation in the regions with larger mismatch. The deformation has been analysed in a framework based on a stress relaxation model published by Fontaine et al. This analysis permits determination of the energies of formation of misfit dislocations. They have been compared with values obtained from ab initio models. From this comparison possible relaxation mechanisms are proposed. A clear dissymmetry is also observed between relaxation of tensile and compressive strain. Pre-relaxation dislocation movements are also detected by diffraction peak broadening. Possible reasons for these behaviours are discussed.