Diffraction from diffusion-barrier-induced mound structures in epitaxial growth fronts

We construct models for the characteristic functions describing the mound structures induced by a surface diffusion barrier in epitaxial growth fronts. These characteristic functions, including the height-height correlation functions, are used to calculate the angular distribution of diffraction intensity. We compare in detail the characteristics of the reciprocal space structure for diffusion-barrier-induced and noise-induced roughening of epitaxial growth fronts. It is shown that except near the out-of-phase (anti-Bragg) diffraction condition, the reciprocal space structure of the diffusion-barrier-induced growth front contains splitting (ring) and broadening characteristics that are dramatically different from that obtained from a scale invariant growth front caused by random noises that exist during growth. This result allows us to differentiate unambiguously, using diffraction techniques, the two mechanisms that can cause the roughening of expitaxial growth fronts.