Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration

Graphene nanoribbons (GNRs), quasi-one-dimensional graphene strips, have shown great potential for nano-scale electronics, optoelectronics and photonics.Atomically precise GNRs can be "bottom-up" synthesized by surfaceassisted assembly of molecular building blocks under ultrahigh vacuum conditions.However, a large-scale and efficient synthesis of such GNRs at low cost remains a significant challenge.Here we report an efficient "bottom-up" chemical vapor deposition (CVD) process for inexpensive and high-throughput growth of structurally defined GNRs with varying structures under ambientpressure conditions.The high quality of our CVD-grown GNRs is validated by a combination of different spectroscopic and microscopic characterizations.Facile, large-area transfer of GNRs onto insulating substrates and subsequent device fabrication demonstrate their promising potential as semiconducting material, exhibiting high current on/off ratio up to 6,000 in field-effect transistor devices.This value is three orders of magnitude higher than values reported so far for other thin film transistors of structurally defined GNRs.Notably, on-surface mass-spectrometry analyses of polymer precursors provide unprecedented evidences for the chemical structures of the resulting GNRs, especially the heteroatom-doping and heterojunctions.These results pave the way toward the scalable and controllable growth of GNRs for future applications.