Monocrystalline ZnTe epilayers were grown onto GaAs(001) substrates and pseudomorphic ZnSe/GaAs(001) heterostructures by means of atomic layer epitaxy. The misfit of the lattice constants in both systems was equal to about -7.5% at a growth temperature of 250C. The epilayer surface was investigated by using reflection high-energy electron diffraction methods during growth. Interruptions of the 1LO Raman spectra of the constituents during growth permitted an analysis to be made of strain in the layer. After growth, the layer/substrate interfaces were investigated by means of high-resolution transmission electron microscopy. The critical thickness for both systems was about 5 shutter cycles. The residual strains at the ZnTe/GaAs and ZnTe/ZnSe interfaces were determined by using various methods. These included the determination of the surface lattice constant from reflection high-energy electron diffraction streak separations, analysis of the 1LOZnTe shift relative to 1LOGaAs, and measurements of the average distance of the misfit dislocations at the interface. These results agreed to within experimental accuracy. It was noted that ZnTe layers of a given thickness exhibited a higher residual strain, after partial relaxation by misfit dislocations, when grown on a ZnSe buffer. The residual strains were equal to -0.5% in the case of GaAs, and -1.7% in the case of ZnSe/GaAs. The types and distributions of dislocations were deduced from high-resolution images by using digital processing methods. In both systems, 60° and Lomer dislocations were the most common line defects.

S.Bauer, M.Huber, C.Rüth, P.Link, W.Gebhardt: Materials Science Forum, 1994, 143-147, 531-6