Transport properties of Z -shaped phosphorene nanoribbon devices

By using first-principles calculations and the non-equilibrium Green's function, we theoretically study the electronic transport properties of a Z-shaped phosphorene nanoribbon (PNR) device, which is called ZSZ-PNR because it is composed of a left zigzag PNR electrode, an intermediate skewed armchair PNR (saPNR), and a right zigzag PNR electrode. First, we investigate the influences of the length and the width of the central saPNR on the ZSZ-PNR transport. The results show that the negative differential conductance (NDC) always appears in the case of the short central saPNR, and is independent of its width, while the NDC is inclined to vanish with the increase of the length. Also, an anomaly on the current-voltage (I-V) curves is observed for the ZSZ-PNR with a short saPNR. Next, the transport properties are analyzed according to the evolution of the energy bands of the electrodes, the molecular energy levels (MELs) of the central saPNR, as well as the transmission coefficients, the transmission eigenstates, and the eigenstates of the self-consistent Hamiltonian of the saPNR. Finally, we use a top gate and two parallel gates to manipulate the transport of the ZSZ-PNR, and find that all these gates can strengthen or suppress the ZSZ-PNR transport.