An ellipsometric study of the growth of hydrogenated amorphous silicon/hydrogenated amorphous silicon‐carbon interfaces and multilayer structures is presented. Kinetic ellipsometry is used at a fixed wavelength to study the growth of the materials at the interface between thea‐Si:H anda‐Si1−xCx:H layers as a function of the carbon content. It is observed that for samples with carbon content below 36%, thea‐SiC:H grows uniformly on top of thea‐Si:H. However, as the carbon content is increased beyond this point, the growth of the alloy material becomes nonuniform. Various growth models were used to fit the experimental data and the best fits were obtained using a multilayer model of varying void fraction to describe the inhomogeneous growth. Multilayers were grown usinga‐Si:H anda‐SiC:H. It was observed that for low carbon concentrations (x<0.36), the successive layers of the multilayer structure are reproducible and the growth remains homogeneous for all the layers.