Transfer-free fabrication of bottom-up graphene nanoribbon transistors

Bottom-up synthesis of graphene nanoribbons (GNRs) provides atomically precise control of widths and edges that give rise to a wide range of electronic properties promising for high-performance field-effect transistors (FETs). However, since the bottom-up synthesis commonly takes place on catalytic metallic surfaces, the integration of GNRs into such devices requires transfer onto insulating substrates, which remains one of the bottlenecks in the field. Here we present a transfer-free method for the placement of seven-atom wide armchair GNRs on insulators substrates. The method involves growing the GNRs on a thin gold film deposited onto an insulating layer followed by gentle wet etching of the gold, which leaves the nanoribbons to settle in place on the underlying insulating substrate. The structural integrity of the nanoribbons on the gold films is examined using Raman spectroscopy and scanning tunneling microscopy (STM), while Raman measurements after etching of the gold verify that the ribbons remain intact on the insulating substrate. We also demonstrate the transfer-free fabrication of short-channel ∼20 nm FETs with the nanoribbons. The on-state current performance is comparable to the transistors fabricated via the much less scalable transfer process.