Noncovalent Surface-modified Approach To Effectively Modulate The Band Structures Of Zigzag SiC Nanoribbons

The successful fabrication of graphene and graphene nanoribbons (GNRs) inexperimenthas taken us into the new material revolution, and stimulatedresearchers’extensive interest onthe low-dimensional carbon-based nanomaterials, even theinorganic nanomaterials. As an analogue of GNRs, the SiC nanoribbons have beenattracting more and more attention in experimental and theoretical researches due tothe excellent properties (e.g. high thermodynamical and chemical stabilities).However,the ground state of zigzag SiC nanoribbons (zSiCNRs)isenergeticallydegenerate between theferromagnetic (FM) and antiferromagnetic (AFM)configurations, which prevents the practical application inspintronicsandmultifunctional nanodevices.In order to conquer this bottleneck, by means of first-principles computations, inthis thesis we first propose a strategy through adsorbing theelectron-withdrawing/donating tetracyanoquinodimethane (TCNQ) ortetrathiafulvalene (TTF) molecules on the surface of the pristine zSiCNRvianoncovalent π-π interaction to modulate the electronic and magnetic properties ofzigzagSiC nanoribbons (zSiCNRs). It is revealed thatall the TCNQ-and TTF-modifiedzSiCNR-systems can exhibit the considerable adsorption energies in the range of-71.3~-184.0kJ/mol, indicating that these zSiCNR-complexes possess the highstructure stabilities.Additionally, the evident charge transfer process between theTCNQ/TTF and zSiCNRs occurs, which leads to the significant change ofelectrostatic potential in the nanoribbon, just like applying the electric field. This canbreak the bottleneck of magnetism degeneracy and effectively engineer the bandstructure. Specifically,when adsorbing the TTF/TCNQ molecule over the center ofzSiCNR, the sole ferromagnetic (FM) metallicity can be achieved. Further, whenmoving the adsorption site of TTF/TCNQ from the center toward the Si/C edges, theFM metallic behavior can be maintained in the TTF-complexes, yet theTCNQ-complexes can exhibit the antiferromagnetic half-metallicity. These intriguing findingswill be advantageous for promoting SiC-based nanomaterials in theapplication of spintronics and multifunctional nanodevices in the near future.