▎ 摘　　要

Graphene being a zero band gap material hinders the use of its intrinsic form for many applications requiring a moderate band gap, such as field effect transistors and optoelectronic devices. Here we demonstrate a scalable method based on chemical vapor deposition for the direct growth of well-registered graphene nanoribbons on SiO2 substrates with precise control over their width, length, and position. The width of the graphene nanoribbons (similar to 20 nm) is defined by the thickness of catalyst film, therefore avoiding the diffraction limit of conventional optical lithographic methods. The carrier mobility (over 1000 cm(2)/V.s) is higher than those previously reported graphene nanoribbons fabricated on SiO2 substrates, thanks to the present transfer-free and contaminant-free direct growth process. This method overcomes many practical limitations of the previously demonstrated methods for the patterning of graphene nanoribbons and is compatible with large-scale fabrication of graphene nanoelectronics.