2D chiral and armchair edges carbon allotrope nanoribbons: robust metallicity and tunable negative differential resistance in net-τ

Abstract

We use density-functional theory combined with nonequilibrium Green's functions (DFT+NEGF) to characterize electronic transport in net-τ nanoribbons and to identify concrete device-relevant metrics. A systematic width- and edge-resolved study reveals a clear crossover: narrow armchair-derived ribbons (motif widths W = 1–3) remain metallic but display sharp, bias-tunable transmission resonances that generate pronounced negative-differential-resistance (NDR). For these narrow geometries we find NDR onset voltages of ≈0.2–0.8 V, peak currents typically in the 1–30 μA range, and peak-to-valley ratios (PVR) up to ≈4–6 in the most pronounced cases. Intermediate widths maximize resonant contrast (zero-bias conductance peaks ≈180–250 μS and conductance valley depths ≈40 μS), whereas wider ribbons (W ≥ 4) acquire multiple dispersive modes and near-ohmic I–V behavior, supporting the largest absolute currents (up to ≈70 μA at 1.0 V) and suggesting application as low-resistance interconnects. These numerical targets—bias windows, current scales and width thresholds—provide actionable guidance for experimental prototyping. Values reported are coherent DFT+NEGF predictions; inelastic scattering, thermal broadening and structural disorder are expected to reduce resonance sharpness and PVR in real devices.