Electronic band gaps in one-dimensional comb structures of simple metals

The electronic properties of comb structures composed of one-dimensional atomic wires of alkali elements are studied. The wires and network of wires are assumed to be formed either on substrates or through networks of metal filled nanotubes. A tight-binding model is used to model the electronic structure of the wires assuming that the atoms are constrained by the substrate or nanotubes to separations exceeding their equilibrium distance. The binding between side wires and the main linear backbone in the comb network opens gaps in the density of states. The band structure of the periodic combs varies significantly with the number of atoms in the side wires as well as the periodicity of the side wires along the backbone. For some specific geometries, complete band gaps may be opened about the Fermi level. Finite combs may be designed to produce devices with electronic properties similar to those of the periodic systems and, in particular, with stop bands in their transmission spectrum.