Phonon confinement in seemingly large crystals can arise by a large defect density and/or morphological features (e.g., nanostructured roughness). Both the increased grain size inhomogeneity and light-induced decomposition with deposition potential, seem to indicate that nanostructuring is the most plausible explanation to phonon confinement. To shed light on the origin of increased nanostructuring, we now introduce the model for the electro-chemically mediated InAs growth.