The dislocation microstructure associated with the loss of coherency of CdTe(OOl), as grown on GaAs(OOl), is characterized using high-resolution transmission electron microscopy. The examination of cross-sectional specimens allowed characteristic local variations in the relative orientation of the overgrowth and the substrate to be quantified and related to associated local changes in the form and distribution of the interface dislocation array. In the interface array, the relative proportion of 60° dislocations and Lomer-Cottrell locks proved to be related to the local misorientation between the CdTe and GaAs. The extent to which this is indicative of the mode of stress relief during the loss of coherency is discussed. Interestingly, it was also found that such variations in the relative proportions of the different types of dislocation proved to be associated with microtwin formation. The significance of this with regard to the strain relief mechanism is also noted.
Bibliographical noteFunding Information:
This work was supported at the University of MN by the Center for Interfacial Engineering under grant No. NSF/CDR-8721551 and the U.S. Army Research Office under grant No. DAAL03-90-G-0001. The work in Italy was supported by the Consorzio Interuniversitario di Fisica della Materia (INFM) and by the Consorzio dell' Area di Ricerca di Trieste. J.E.A. acknowledges the TBM Corporation for support via a graduate fellowship and Sandia National Laboratory Livermore for support via a Summer Fellowship. W.M.S. thanks the Associated Western Universities Programme for support while at Sandia. The authors would particularly like to thank M. J. Mills and G. J. Thomas of SNLL for the use of the JEOL 4000EX in that laboratory.