▎ 摘　　要

Graphene nanoribbons (GNRs) were fabricated by metal mask lithography and plasma etching. GNRs with width similar to 20 nm show field-effect conductance modulation of similar to 12 at room temperature and >10(6) 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 similar to 40 nm. High field family I-Vs exhibited current saturation tendency and current density as high as 2 A/mm has been measured at low temperature. c 2010 American Institute of Physics. [doi: 10.1063/1.3352559]