The structural characteristics of ZnTe epilayers which had been grown onto (100)GaAs by means of metalorganic vapor-phase epitaxy was reported. A detailed study of the heterostructure, which was based upon high-resolution and conventional electron microscopy and upon ion-channelling Rutherford back-scattering spectrometry, permitted a correlation to be made between the type and spatial distribution of extended defects which occurred at the interface, and the amount of residual lattice strain in the ZnTe epilayers. Pure edge Lomer and 60 mixed misfit dislocations were identified at the interface, together with partial dislocations that bounded stacking faults. Their overall density and distance distribution indicated the existence of a residual compressive strain at the heterostructure interface. By comparing this interface strain with the corresponding surface value for the same samples, the occurrence of an inhomogeneous strain relaxation along the growth direction was demonstrated. It was shown that such a strain gradient could be entirely attributed to threading dislocations in the ZnTe epilayers; with their distribution being strictly related to the amount of residual strain along the epilayer growth direction. These conclusions were also supported by an analysis of the ZnTe surface strain. Its dependence upon the epilayer thickness was consistent with that which was to be expected on the basis of a phenomenological model for epilayer residual strain relaxation by threading dislocations.

N.Lovergine, L.Liaci, J.D.Ganière, G.Leo, A.V.Drigo, F.Romanato, A.M.Mancini, L.Vasanelli: Journal of Applied Physics, 1995, 78[1], 229-35