Transport Properties Of Silicene Nanoribbons Research Articles

Role of line defect in the bandgap and transport properties of silicene nanoribbons

By using the tight-binding model and non-equilibrium Green's function method (NEGF), we study the band structures and transport properties of a silicene nanoribbon with a line defect where a bulk energy gap is opened due to the sublattice symmetry breaking. The flat subband bends downwards or upwards due to the effect of the line defect. The spin-orbit coupling induces quantum spin Hall states. Especially, the energy band depends on the distance between the line defect and the edge of the nanoribbon. The effects of the on-site energies on the band spectra of the two defect configurations are different. There always exists one band gap for different on-site energies for the defect configuration of case 1. However, a gapless state and a band gap can be modulated by changing the on-site energy, the sublattice potential and spin-orbit couplings for the defect configuration of case 2. Accordingly, the variation trends of the conductance including zero conductance can be well understood in terms of the combined effect of the sublattice potential, the on-site energy and spin-orbit couplings on the band structures. Thus it is easy and effective to modulate the transport property of the silicene nanoribbon with the defect configuration of case 2 by utilizing the sublattice potential, the on-site energy and spin-orbit couplings. This study is of great significance for the fabrication and the modulation of the transport property of silicene-based devices.

Impact of point defects on the electronic and transport properties of silicene nanoribbons

We study the impact of various point defects on the structural, electronic and ballistic transport properties of armchair silicene nanoribbons, using the density functional theory and the non equilibrium Green’s function method. The effect of a Stone–Wales defect, an interior/edge vacancy and an edge dangling bond is examined. Our results show that structural imperfections can alter the electronic structure (energy band structure and density of states) of the nanoribbons and can either increase or decrease the ballistic current. The dependence of the transport properties on the position of the defects (sublattice A or B) and on their distance from the contact is also investigated.

Effect of SW defect on structural and transport properties of silicene nanoribbons

Using density functional theory and nonequilibrium Green's function technique, we performed theoretical investigations on the structural and transport properties of zigzag silicene nanoribbons (SiNRs) with Stone–Wales (SW) defect. The calculated formation energy is significantly lower than that of graphene and silicene, which implies the high stability of such defect in SiNRs. Negative differential resistance (NDR) can be observed within certain bias voltage range in both perfect and SW-defected SiNRs. In order to elucidate the mechanism, the NDR behavior, the transmission spectra and molecular projected self-consistent Hamiltonian (MPSH) states are discussed in details.

Electronic and Transport Properties of Silicene Nanoribbons

Electronic and Transport Properties of Silicene Nanoribbons

Quantized conductance and field-effect topological quantum transistor in silicene nanoribbons

Silicene is a quantum spin-Hall insulator, which undergoes a topological phase transition into other insulators by applying external fields. We investigate transport properties of silicene nanoribbons based on the Landauer formalism. We propose to determine topological phase transitions by measuring the density of states and conductance. The conductance is quantized and changes its value when the system transforms into different phases. We show that a silicene nanoribbon near the zero energy acts as a field-effect transistor. This transistor is robust since the zero-energy edge states are topologically protected. Our findings open a way to future topological quantum devices.