▎ 摘　　要

In this letter, we report a pilot study on epitaxy of monolayer graphene nanoribbons (GNRs) on hexagonal boron nitride (h-BN). We found that GNRs grow preferentially from the atomic steps of h-BN, forming in-plane heterostructures. GNRs with well-defined widths ranging from similar to 15 nm to similar to 150 nm can be obtained reliably. As-grown GNRs on h-BN have high quality with a carrier mobility of similar to 20 000 cm(2) V-1 s(-1) for similar to 100-nm-wide GNRs at a temperature of 1.7 K. Besides, a moire pattern induced quasi-one-dimensional superlattice with a periodicity of similar to 15nm for GNR/h-BN was also observed, indicating zero crystallographic twisting angle between GNRs and h-BN substrate. The superlattice induced band structure modification is confirmed by our transport results. These epitaxial GNRs/h-BN with clean surfaces/interfaces and tailored widths provide an ideal platform for high-performance GNR devices. (C) 2016 AIP Publishing LLC.