A study was made of misfit stresses in the CdTe(100)/GaAs(100) system. This highly mismatched system initially formed a so-called coincidence interface in which 7 lattices of CdTe matched 8 lattices of GaAs. The epilayer was elastically strained by the mismatch which remained between the 2 lattices. The misfit stress then gradually relaxed, with the generation of misfit dislocations. A new model was derived for the description of this misfit relaxation mechanism, and was verified experimentally. Upon introducing the effects of interface modification, it was found that a simple force balance between the substrate and the epilayer governed the misfit stress. It was assumed that the relaxation process during growth was similar to that in CdTe/CdZnTe, as the residual misfit was quite small. By extending the stress relaxation model for CdTe/GaAs, it was possible to explain the strain in CdTe/ZnTe/GaAs; which contained 2 highly mismatched interfaces. The threading dislocations in HgCdTe, arising from the CdTe buffer, decreased with increasing CdTe thickness. By assuming that the misfit dislocations were generated by bending threading dislocations, the dislocation reduction could be explained in terms of the above misfit stress relaxation model. In spite of the extremely large mismatch, the structural quality of CdTe(100) on GaAs(100) was improved; due to the relatively small strain which remained in the coincidence interface.

H.Nishino, I.Sugiyama, Y.Nishijima: Journal of Applied Physics, 1996, 80[6], 3238-43