Reduction in the crystal defect density of ZnSe layers grown by molecular beam epitaxy

We present a study of the molecular beam epitaxial (MBE) growth of ZnSe layers on GaAs- and Si-substrates. For the growth on GaAs substrates we investigated the effects of introducing buffer layers of AlxGa1-xAs and InxGa1-xAs. The characterization by reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy showed that the best ZnSe crystal quality was obtained on buffer layers of AlxGa1-xAs and InxGa1-xAs with x = 0.01. Moreover, an analysis by secondary ion mass spectroscopy revealed that the use of AlGaAs buffer layers effectively suppress the Ga segregation onto the ZnSe layers surface. On the other hand, for the growth of ZnSe on Si substrates, we achieved a significant improvement in the crystal quality of ZnSe by irradiating the Si substrates with plasma of nitrogen prior to the growth.

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