Self-organization of adsorbate crystal morphology on a heteroepitaxial surface

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In heteroepitaxial growth, materials of the substrate and of the overlayer crystal are different. In order to decrease the effect of strain energy induced by the lattice misfit, nanostructures are sometimes fabricated on a substrate. We found that the crystal dewetting is different from the liquid dewetting; for instance, an adsorbate crystal island arranges itself in an asymmetric position on a substrate pillar, or a crystal island collapses only partially. When Si islands evaporate on SiO2 substrate at high temperatures, they diffuse around with a diffusion constant almost independent of the island size. We attributed this anomalous diffusion to the pinning-depinning phenomenon of the island edge at rough corners of the Si/SiO2 interface produced by chemical reactions. We also studied scaling behavior of the grain coarsening during the unidirectional solidification of multicrystals on a substrate.