Dislocation reduction in HgCdTe epilayers on GaAs by using CdTe/CdZnTe strained-layer superlattices in CdTe layers

Abstract

The structure of CdTe/CdZnTe strained layer superlattices (SLSs) which block the threading dislocations has been studied. Since the residual strain in the heteroepitaxial CdTe offsets the SLS-induced strain, SLSs located near the interface of CdTe/GaAs should be constructed with large misfit force in place. The surface dislocation density of CdTe was found to be reduced by a factor of 2.5 by using the two SLSs, and by a factor of 4.3 for four SLSs. The etch pit density of a HgCdTe layer grown on this SLS buffer layer was reduced, a beneficial side effect of reducing the dislocations in the buffer layer. Thus, strained-layer superlattices effectively block dislocations if designed properly. The dislocation density can be further reduced by increasing the number of SLSs.