Surface roughening during low-temperature Si epitaxial growth on singular vs vicinal Si(001) substrates

The evolution of surface roughness on epitaxial Si films grown at 300 degrees C by ultrahigh vacuum ion-beam sputter deposition onto nominally similar, [100]-, and [110]-miscut Si(001) is inconsistent with conventional scaling and hyperscaling laws for kinetic roughening. Unstable growth leading to the formation of mounds separated by a well-defined length scale is observed on all substrates. Contrary to previous high-temperature growth results, the presence of steps during deposition at 300 degrees C increases the tendency toward unstable growth resulting in a much earlier development of mound structures and larger surface roughness on vicinal substrates.