Twin formation during SiC nanowire synthesis

Silicon carbide (SiC) is a covalent material with many polytypes. The cubic phase, which has essentially zero formation energy, dominates in SiC nanowires. These nanowires contain twin boundaries that axe far separated, in contradiction to the zero formation energy. This paper presents a model to account for the well-separated and equal-spaced twins in SiC nanowires. The model is based on the energy minimization of interfaces and edges near twin boundaries. Our theoretical result shows that the distance between neighboring twin boundaries is equal to 18%-31% of the diameter for SiC nanowires. This result is in agreement with our experimental data of SiC nanowires and also those of microwhiskers in the literature. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2979716]