A comparison is performed between the experimentally determined variation of the layer thickness at 50 at% with the primary ion energy and the prediction of this variation and of the layer thickness at 50% amplitude by the Mixing-Roughness-Information depth (MRI) model for SIMS depth profiles of Ge/Si multilayers. Reasonable agreement was obtained by taking into account the influence of the primary ion energy on both preferential sputtering and atomic mixing length. In both cases, the determined layer thickness increases with ion energy for the component with higher sputtering rate (Ge) and decreases for the one with lower sputtering rate (Si).