Structural and tunneling properties of Si nanowires

Abstract

We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green's function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the 110 direction showing the smallest decay with length and the largest conductance and current.

Tunneling magnetoresistance in Si nanowires

“…The SiNWs have been generated without considering surface reconstruction by applying Wulff's law for minimal free energy equilibrium [28], where a cylindrical shape with a core that retains the diamond structure is the most stable configuration [29]. In order to ensure chemical stability, dangling bonds have been passivated with H. The growth direction has been chosen to be á ñ 110 , which was reported to have the smallest tunneling decay coefficient among all possible orientations [26,30] and therefore is the orientation able to support the largest conductance. Figure 1(a) displays the cross section of a SiNW grown in the á ñ 110 direction with diameter = D 1.0 nm, where the blue and red spheres represent Si and H atoms, respectively.…”

“…SiNWs are compatible with conventional Si technology and have been adapted in a variety of nanoscale devices, such as transistors [22], photodetectors [23] and solar cells [24]. The ability to control their diameter, composition and length makes them a desirable platform for spintronics studies [25], and previous work has demonstrated that the tunneling properties depend on the structural parameters [26]. In addition, the inclusion of n and p dopants has shown to modify the conductance [27].…”

A theoretical model for predicting Schottky-barrier height of the nanostructured silicide-silicon junction

“…Indeed, understanding on SBH of the nanostructure is still in an early stage. due to the increment of the band gap (E g ) by the quantum confinement effect 11,12 .…”

“…Namely, the study on SBH of the nanostructured junction is still lacking. 13 In recent years, a number of studies have attempted to calculate SBH by using the density functional theory (DFT) 11,12,[14][15][16][17][18][19][20][21][22][23][24] . Unlike the classical models such as Schottky-Mott (SM) rule 25,26 and metal induced gap states (MIGS) model 27,28 , the DFT method has the merits of considering and examining interatomic effects between semiconductor and metal atoms.…”

“…Unlike the classical models such as Schottky-Mott (SM) rule 25,26 and metal induced gap states (MIGS) model 27,28 , the DFT method has the merits of considering and examining interatomic effects between semiconductor and metal atoms. While most of the DFT studies on SBH focused on bulk junction, E. Montes et al 11 and U. Landman et al 12 have demonstrated a DFT calculation for a nanostructured junction and showed that φ Nano In this work, we perform the DFT calculations for various nanostructured silicide-silicon junctions to investigate their SBHs. As for the silicides, PtSi, NiSi, TiSi 2 and YSi 2 are used.…”