Self-organized SiC nanostructures on silicon

Self-organization in a system with chemical interactions between the substrate (silicon) and deposit (carbon) is demonstrated by growing SiC dots on silicon substrates. The large lattice mismatch between silicon and SiC of 20% stimulates a three-dimensional nucleation on the substrate. This spontaneous formation of islands is a powerful tool for the formation of dots. However, the chemical interaction leads to an instability of the Si surface during the nucleation and the growth: the need for Si for the SiC formation as well as the Si evaporation results in a depletion of the area surrounding the SiC islands. As a result, well-defined pyramids with a fourfold symmetry are formed on Si(001) substrates with SiC nuclei on the top. The nucleation sites were controlled by the formation of equally spaced monatomic and biatomic steps on Si(001) and Si(111), respectively. The resulting terraces promote an alignment of the SiC dots along the step edges. By applying atomic force microscopy we demonstrate a lateral ordering of SiC dots in linear chains and in dense dot arrays. Depending on the process conditions, the SiC dot separation was adjusted between 20 and 500 nm. (C) 2004 Elsevier Ltd. All rights reserved.