Surface structural and morphological characterization of ZnTe epilayers grown on {100} GaAs by MOVPE

Abstract

The surface structural and morphological characterization of ZnTe epilayers grown on {100}GaAs by atmospheric pressure MOVPE is reported. Scanning electron microscopy (SEM), reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been performed on the as-grown ZnTe epilayer surfaces. RHEED pattern allowed to estimate the ZnTe crystalline quality, whereas the layer-to-substrate epitaxial relationships have been demonstrated from both RHEED and X-ray diffraction. SEM and REM observations in combination with alpha-step surface profiling measurements allowed to obtain a quantitative description of ZnTe surface irregularities, whose dimensions range from a few nm to just above 30 nm in height, being several hundred nm wide across the surface. Also, the ZnTe surface roughness depends linearly on the epilayer thickness and approaches the initial surface roughness of the GaAs substrates when the thickness tends to zero. Finally, no evident surface anisotropy has been revealed in the present samples, apart from a characteristic (011) elongation effect of some growth defect features at the epilayer surfaces.