Study of the crystal quality and Ga-segregation in ZnSe films grown by molecular beam epitaxy on Al xGa 1− xAs and In xGa 1− xAs buffer layers on GaAs substrates

Abstract

In the present work, we report a study of the molecular beam epitaxial growth of ZnSe on GaAs substrates using Al x Ga 1− x As and In x Ga 1− x As ternary alloys as buffer layers. When growing ZnSe directly on a thermally desorbed GaAs substrate, surface segregation of Ga across the film towards the ZnSe surface was observed by secondary ion mass spectroscopy. We demonstrate that the use of AlGaAs buffer layers is very effective to suppress the Ga surface segregation. The characterization of the films by reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, photoluminescence and photoreflectance spectroscopy revealed that the best crystal quality ZnSe films were obtained for buffer layers with In or Al concentrations of 1%.