Quantum transport in graphene nanoribbons patterned by metal masks

Graphene nanoribbons (GNRs) were fabricated by metal mask lithography and plasma etching. GNRs with width $∼20nm$ show field-effect conductance modulation of $∼12$ at room temperature and $>106$ at 4.2 K. Conductance quantization due to quantum confinement in low field transport was observed. Landauer formula was utilized to fit the experimental data and excellent agreement was obtained. The extracted subband energy separation was found to deviate from the predicted values of perfect armchair GNRs. Transmission probability is much smaller than unity due to scattering by GNR edge/bulk disorder and impurities, indicating a mean free path $∼40nm$⁠. High field family I-Vs exhibited current saturation tendency and current density as high as 2 A/mm has been measured at low temperature.