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 lay ers on GaAs- and Si-substrates. For the growth on GaAs substrates we invest igated the effects of introducing buffer layers of AlxGa1-xAs and InxGa1-xA s. The characterization by reflection high-energy electron diffraction, ato mic force microscopy, transmission electron microscopy, and photoluminescen ce spectroscopy showed that the best ZnSe crystal quality was obtained on b uffer layers of AlxGa1-xAs and InxGa1-xAs with x = 0.01. Moreover, an analy sis by secondary ion mass spectroscopy revealed that the use of AlGaAs buff er layers effectively suppress the Ga segregation onto the ZnSe layers surf ace. On the other hand, for the growth of ZnSe on Si substrates, we achieve d a significant improvement in the crystal quality of ZnSe by irradiating t he Si substrates with plasma of nitrogen prior to the growth.