Nanoscale Single-Crystal Silicon Carbide on Silicon and Unique Properties of This Material

The paper reviews the latest advances in the growth of epitaxial SiC films on Si by the coordinated atomic substitution method. The conceptual issues and procedure of the new method for synthesizing epitaxial SiC films on Si are described. It is shown that this method significantly differs from the classical thin film growth schemes. Film growth in accordance with the classical mechanism is provided by deposition of atoms on the surface of a substrate. The new method consists in the coordinated atomic substitution of a portion of the atoms of the silicon matrix by carbon atoms to form an epitaxial silicon carbide film. The new growth method is compared with the classical thin film growth mechanisms. It is shown that the main distinctive feature of SiC films synthesized by this method is the formation of an excess concentration of silicon vacancies in it, whereas SiC grown by the standard methods comprises mostly carbon vacancies. It is shown that the interaction of carbon atoms and silicon vacancies leads to the formation of ordered ensembles of carbon-vacancy structures in SiC layers grown by the coordinated atomic substitution method. The formation of these structures is attributed to both the occurrence of a chemical substitution reaction and the contraction of the Si lattice cell during the transformation of it into a SiC lattice cell. The presence of carbon-vacancy structures in SiC imparts a number of new unique properties to the silicon carbide. In particular, a Si layer exhibiting the electronic properties of a "semimetal" is formed at the SiC-Si interface. In addition, carbon-vacancy structures provide unique optical, electrical, and magnetic properties. In particular, two quantum effects-a hysteresis of the static magnetic susceptibility and the occurrence of Aharonov-Bohm oscillations in the field dependences of the static magnetic susceptibility-are found to occur in weak magnetic fields at room temperature. The first of the effects is associated with the Meissner-Ochsenfeld effect; the second is associated with the presence of carbon-vacancy structures and microdefects in the form of nanotubes and micropores formed in these structures during SiC synthesis under the SiC layer.