Electronic and transport properties of bismuth nanolines for applications in molecular electronics

The density functional theory and Green’s function approaches have been used for the investigation of the electronic and transport properties of bismuth nanowires deposited on a Si(001) surface. The results of calculations show that the conductance properties of deposited bismuth wires depend on the morphology of the silicon surface and the existence of dangling bonds on the surface, which may lead to current leakage across these bonds. Thus in order to use the bismuth lines as atom-wire interconnections for molecular electronics applications it is important to use the hydrogenated Si(001) surface. Despite the fact that Bi nanowires exhibit semiconductor features, the current through these nanowires can be operated within a given voltage region. Moreover Bi nanowires may possibly be used as a nanoline template for other metals.

Figure 1

(Color online) Cluster models (top and side views) for Bi wire on (a) clean and (b) hydrogenated Si surface.

Figure 2

(Color online) Contour plots of selected molecular orbitals of Bi wire on a clean Si(001) surface.

Figure 3

(Color online) Top and side views of molecular orbitals of a Bi-line on a clean Si(001) for comparison with STM images obtained at $-0.51$ and $2\mathrm{V}$ (see Ref. 8), respectively.

Figure 4

(Color online) Contour plots of selected molecular orbitals of Bi wire on hydrogenated Si(001) surface.

Figure 5

Zero-bias conductance, partial density of states of Bi (Bi-PDOS), and density of states (DOS) for Bi-line on an H-terminated Si(001) (a)–(c) and on a clean Si(001) surface (d)–(f), respectively. The Fermi level (vertical dotted line) has been chosen as zero energy.