DIFFRACTION FROM DIFFUSION-BARRIER-INDUCED MOUND STRUCTURES IN EPITAXIAL-GROWTH FRONTS

We construct models for the characteristic functions describing the mo und structures induced by a surface diffusion barrier in epitaxial gro wth fronts. These characteristic functions, including the height-heigh t correlation functions, are used to calculate the angular distributio n of diffraction intensity. We compare in detail the characteristics o f the reciprocal space structure for diffusion-barrier-induced and noi se-induced roughening of epitaxial growth fronts. It is shown that exc ept near the out-of-phase (anti-Bragg) diffraction condition, the reci procal space structure oi the diffusion-barrier-induced growth front c ontains splitting (ring) and broadening characteristics that are drama tically different from that obtained from a scale invariant growth fro nt caused by random noises that exist during growth. This result allow s us to differentiate unambiguously, using diffraction techniques, the two mechanisms that can cause the roughening of expitaxial growth fro nts.