Graphene nanoribbon field-effect transistors fabricated by etchant-free transfer from Au(788)

Abstract

We report etching-free and iodine-free transfer of highly aligned array of armchair-edge graphene nanoribbons (ACGNRs) and their field-effect transistor (FET) characteristics. They were prepared by on-surface polymerization on Au(788) templates. The ACGNRs were mechanically delaminated and transferred onto insulating substrates with the aid of a nano-porous support layer composed of hydrogen silsesquioxane (HSQ). The key process in the mechanical delamination is the intercalation of octanethiol self-assembled monolayers (SAMs), which penetrate the HSQ layer and intercalate between the ACGNRs and Au(788). After the transfer, the octanethiol SAMs were removed with Piranha solution, enabling the reuse of the Au single crystals. The FETs fabricated with the transferred ACGNR array showed ambipolar behavior when the channel length was as long as 60 nm. Quasi-one-dimensional conductivity was observed, which implies a good alignment of GNRs after the transfer. In contrast, short-channel ACGNR FETs (channel length ∼20 nm) suffer from a geometry-dependent short-channel effect. This effect is more severe in the FETs with ACGNRs parallel to the channel, which is an ideal geometry, than in ones perpendicular to the channel. Since the ID-VD curve is well fitted by the power-law model, the short-channel effect likely stems from the space-charge limited current effect, while the wide charge-transfer region in the GNR channel can be another possible cause for the short-channel effect. These results provide us with important insights into the designing short-channel GNR-FETs with improved performance.

Controlling a Chemical Coupling Reaction on a Surface: Tools and Strategies for On-Surface Synthesis

“…Copyright 2013 AIP Publishing. (b) Reprinted with permission from ref (416). Copyright 2018 AIP Publishing.…”

Atomically precise graphene nanoribbons: interplay of structural and electronic properties

“…2b) or a ribbon with periodic width modulation (e.g. 79). Creating wider ribbons following this design strategy requires larger precursors which are more difficult to synthesize (e.g.…”

“…76 A more successful strategy of aligning GNRs is to synthesize them on vicinal surfaces, such as Au(788) or Au(322). [77][78][79][80] Because the terraces of these surfaces are Au(111) facets, results obtained on Au (111) can readily be replicated on Au(788), provided that the width of the GNR is not larger than the width of the terrace.…”

Field-Effect Transistors Based on Networks of Highly Aligned, Chemically Synthesized N = 7 Armchair Graphene Nanoribbons

“… 14 The higher I ON / I OFF ratio in the wider ribbons appears to contradict theoretical expectations—wider ribbons should have a lower band gap—but this can be explained by the different experimental conditions of this emerging technology. In this work, we present GNR-FETs based on dense, highly aligned arrays of 7-AGNRs, similar to those in ref ( 15 ). There is great merit in highly aligned, parallel GNRs that form one transistor (or sensor) with multiple nanoribbon channels: such parallelism will be required to meet the demands of drain currents in the transistor on-state, i.e.. a single ribbon will not be able to deliver the required performance.…”