Diverse structural and electronic properties of pentagonal SiC2 nanoribbons: A first-principles study

Abstract

Through the first-principles calculations, a generalized theoretical framework is used to systematically investigate the structural and electronic properties of the buckled SiC2 pentagon-based nanoribbons (p-SiC2 nanoribbons), including the formation energies, optimal structural parameters, phonon spectrum, electronic band structures, orbital-projected density of states (DOSs) and partially charge density distributions. The dimensional reduction of the pentagonal SiC2 nanosheet result in the four distinct edge structures of the p-SiC2 nanoribbons, including ZZ-ribbon, ZA-ribbon, AA-ribbon and SS-ribbon, in which the p-SiC2 SS-ribbon achieves the greatest thermal and dynamic stability among the other ones. Energy gaps of the p-SiC2 nanoribbons are created mainly owing to the competition in the edge structures, finite-size confinements and asymmetry of chemical bonds in the tetrahedral lattice. The critical width is found at W = 14, where the band gaps are dramatically reduced as the widths increase below the critical one, while the band gaps are hardly sensitive with the enlarged widths beyond the critical one. The unusual properties of the p-SiC2 nanoribbons is very potential for applications in optoelectronic devices, especially in photovoltaics.