We investigated edge configuration and quantum confinement effects on electron transport in armchair-edged graphene nanoribbons (A-GNRs), by using a computational approach. We found that the edge bond relaxation has a significant influence not only on the band-gap energy, but also on the electron effective mass. We also found that A-GNRs with N = 3m family (N is number of atoms in its transverse direction and m a positive integer) exhibits smaller effective mass, by comparing at the same band-gap energy. As a result, A-GNRs with N = 3m family are found to be favorable for use in channels of field-effect transistors.

In this paper, we investigate the upper limit performance of bilayer graphene (BLG) and graphene nanoribbon (GNR) field-effect transistors (FETs) based on a first-principles approach. We have found that GNR-FETs with ribbon widths of about 3–4 nm exhibit better device performance than n-channel Si metal–oxide–semiconductor FETs and InP-high-electron-mobility transistors (HEMTs). Although a BLG-FET shows an inferior performance potential to GNR-FETs with a similar band gap, it is comparable to InP-HEMTs. The present simulation study indicates that both GNR and BLG are expected to be a post-Si channel material for high-speed digital switches in logic circuits.

Although graphene is a zero-gap semiconductor, band-gap energies up to several hundreds millielectron volts have been introduced by utilizing quantum mechanical confinement in nanoribbon structures or symmetry breaking between two carbon layers in bilayer graphenes. However, the opening of a band-gap causes a significant reduction in carrier velocity due to the modulation of bandstructures in their low energy spectrums. In this paper, we study intrinsic effects of the band-gap opening on ballistic electron transport in graphene nanoribbons (GNRs) and bilayer graphenes (BLGs) based on a computational approach, and discuss the ultimate device performances of field-effect transistors (FETs) with those semiconducting graphene channels. We have shown that an increase of external electric field in BLG-FET to obtain a larger band-gap energy substantially degrades its electrical characteristics because of de-acceleration of electrons due to a Mexican hat structure, and therefore GNR-FET outperforms in principle BLG-FET.

Graphene nanomeshes (GNMs) are expected to be a high-performance channel material for metal-oxide-semiconductor field-effect-transistors (MOSFETs), since they can open up a band gap in a large sheet of graphene thin film by simply introducing two-dimensional periodical nanoscale holes. In this paper, we theoretically investigate the electronic band structures and the electron transport properties of GNMs based on a tight-binding approach. We demonstrate that GNMs have the capability of band structure engineering by controlling its neck width and furthermore the potential ability providing high current drivability when applied to a field-effect-transistor channel.

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