Growth and characterisation of ZnTe and ZnTeCdTe superlattices on GaAs substrates

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Epitaxial layers of ZnTe and CdTeZnTe superlattices have been grown by atmospheric pressure MOVPE on {;100}; GaAs substrates and characterised by RHEED, SEM and TEM. Although they are of high crystal quality, the ZnTe layers exhibit a characteristic ridged morphology due to anisotropic facetting. These layers are found by TEM to contain a high density of misfit dislocations extending throughout a 2 μm thick layer. In contrast, CdTeZnTe superlattices grown under the same conditions are shown to have a much improved surface morphology but with a characteristic assymetric rectangular network of slip traces and cracks. These are attributed to the thickness of the CdTe layers and the high growth temperature causing the strain in the system to be largely relieved.