Study of the crystal quality and Ga-segregation in ZnSe films grown by molecular beam epitaxy on AlxGa1-xAs and InxGa1-xAs buffer layers on GaAs substrates

In the present work, we report a study of the molecular beam epitaxial grow th of ZnSe on GaAs substrates using AlxGa1-xAs and InxGa1-xAs ternary alloy s as buffer layers, When growing ZnSe directly on a thermally desorbed GaAs substrate, surface segregation of Ga across the film towards the ZnSe surf ace was observed by secondary ion mass spectroscopy. We demonstrate that th e use of AlGaAs buffer layers is very effective to suppress the Ga surface segregation. The characterization of tile films by reflection high-energy e lectron diffraction, atomic force microscopy. transmission electron microsc opy, photoluminescence and photoreflectance spectroscopy revealed that the best crystal quality ZnSe films were obtained for buffer layers with In or Al concentrations of 1%. (C) 2001 Elsevier Science B.V. All rights reserved .