Strain-induced misfit dislocations in the CdTe/ZnTe (001) superlattices

At the lattice-mismatched heterojunction, the strain may cause one of two results: (i) give one more degree of freedom to the novel growth techniques to control the process of bandgap engineering, if the strained layers are kept sufficiently thin, or (ii) cause the occurrence of misfit dislocations, if the strained layers exceed a certain critical thickness. In the present investigation, the electronic band structures of the strained CdTe/ZnTe (001) superlattices (SLs) are investigated using the sp³s* tight-binding method, which includes the strain and spin-orbit coupling effects. The calculated band structures are studied versus the biaxial strain, SL layer thicknesses, and valence-band offset (VBO). Special attention has been given to the case of free-standing SLs, which were the most useful structures in interpreting the experimental results. Our theoretical results are compared to the photoluminescence experimental data and shown to be consistent with the strain morphology along the SL growth direction, as well as with the optical and structural qualities of the experimental samples.