Charge transport in doped zigzag phosphorene nanoribbons

The effects of lattice distortion and chemical disorder on charge transport properties of two-terminal zigzag phosphorene nanoribbons (zPNRs), which shows resonant tunneling behavior under an electrical applied bias, are studied. Our comprehensive study is based on an {\it ab~initio} quantum transport calculations on the basis of the Landauer theory. We use nitrogen and silicon substitutional dopant atoms, and employ different physical quantities such as $I-V$ curve, voltage drop behavior, transmission spectrum, transmission pathway, and atomic current, to explore the transport mechanism of zPNR devices under a bias voltage. The calculated transmission pathways show the transition from a ballistic transport regime to a diffusive and in some particular cases to localized transport regimes. Current flowing via the chemical bonds and hopping are monitored, however, the conductance originates mainly from a charge traveling through the chemical bonds in the vicinity of the zigzag edges. Our results show that, in the doped systems, the device conductance decreases and negative differential resistance characteristic becomes weak or eliminates. Besides, the conductance in a pure zPNR system is almost independent of the ribbon width.