Self-organization of adsorbate crystal morphology on a heteroepitaxial surface

在异质外延生长中，衬底和覆盖层晶体的材料是不同的。为了减小晶格失配引起的应变能效应，有时在衬底上制造纳米结构。我们发现，晶体去湿是不同的液体去湿，例如，吸附物晶体岛安排本身在一个不对称的位置上的衬底柱，或晶体岛崩溃只有部分。当Si岛在SiO2衬底上在高温下蒸发时，它们以几乎与岛尺寸无关的扩散常数向周围扩散。我们把这种异常扩散归因于化学反应产生的Si/SiO2界面粗糙角处的岛边缘的钉扎-脱钉扎现象。我们还研究了多晶在基体上定向凝固过程中晶粒粗化的标度行为。

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.