Optimum Contact Configurations for Quasi-One-Dimensional Phosphorene Nanodevices

We employ atomistic quantum transport simulations based on non-equilibrium Green’s function (NEGF) formalism of quasi-one-dimensional (quasi-1D) phosphorene, or phosphorene nanoribbons (PNRs), to explore routes towards minimizing contact resistance (R(C)) in devices based on such nanostructures. The impact of PNR width scaling from ~5.5 nm down to ~0.5 nm, different hybrid edge-and-top metal contact configurations, and various metal–channel interaction strengths on the transfer length and R(C) is studied in detail. We demonstrate that optimum metals and top-contact lengths exist and depend on PNR width, which is a consequence of resonant transport and broadening effects. We find that moderately interacting metals and nearly edge contacts are optimum only for wider PNRs and phosphorene, providing a minimum R(C) of ~280 Ωμm. Surprisingly, ultra-narrow PNRs benefit from weakly interacting metals combined with long top contacts that lead to an added R(C) of only ~2 Ωμm in the 0.49 nm wide quasi-1D phosphorene nanodevice.