Sub-10 nm Graphene Nanoribbon Array Field-Effect Transistors Fabricated by Block Copolymer Lithography

摘要

Graphene is of great interest for electronic devices because of its extraordinary properties, including high mobility, high thermal conductivity and high transparency, from an atomi-cally-thin two-dimensional material. However, the intrinsic zero bandgap makes it very difficult to achieve the high on/ off current ratio required from field-effect transistors (FETs) useful in digital electronics. In order to overcome this hurdle, many attempts have been made to open the bandgap of graphene by techniques including hydrogenation, doping and lithographic patterning. Patterning the graphene into nanor-ibbons with sub-10 nm widths was suggested as a strategy to open the bandgap, and was verified experimentally, in which the samples showed a bandgap due to quantum confinement and a high on/off current ratio. Kim et al. and Avouris et al. fabricated graphene nanoribbons (GNRs) using electron-beam lithography. Nanowires were also used as an etch mask to make GNRs by exposing graphene to an oxygen plasma. Additionally, nanoribbons were formed by chemically or physically unzipping multi-walled carbon nanotubes, a process in which the width of the nanoribbons depends on the diameter of the nanotubes from which the nanoribbons originated.