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 nanoscale electronics, opto­electronics,
and photonics. Atomically precise GNRs can be “bottom-up”
synthesized by surface-assisted assembly of molecular building blocks
under ultra-high-vacuum conditions. However, 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 ambient-pressure
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 materials, exhibiting high current on/off ratios
up to 6000 in field-effect transistor devices. This value is 3 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
evidence 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.