In situ laser reflectometry study of the morphology of Ge/GaAs layers during their heteroepitaxial growth

The morphology of Ge layers, a few micrometers thick, grown by chemical‐vapor deposition on GaAs substrates, is very sensitive to the growth conditions. The evolution of the intensity of the dynamic in situ reflectometry reveals different growth features. We present here an analysis of the basic elements from which it is possible to deduce important physical parameters of the Ge layers: the shape of the growth defects, their density, the optical index of the homogeneous layer, and the effective index of the rough layer. The respective contributions of the scattered and refracted intensities to the measured intensity are described semiempirically. Typical experimental curves and their corresponding time‐dependent growth rate, optical index, and morphology are given.