Influence of Band-Gap Opening on Ballistic Electron Transport in Bilayer Graphene and Graphene Nanoribbon FETs

Abstract

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.

Structural and Electronic Properties of Superlattice Composed of Graphene and Monolayer MoS2

“…Since the presence of a band gap is a crucial property in electronic and/or optoelectronic devices, it is significant to introduce a band gap in graphene. This problem could be solved by doping, tailoring or controlling the dimensionality of graphene, − which, however, usually result in crystallographic damage to the materials and unexpected loss in the excellent electrical properties. − Therefore, it is important to find a solution that not only brings a tunable band gap but also reserves the integrity of graphene.…”

Direct observation of ultraclean tunable band gaps in bilayer graphene

“…The high quality of Gr/hBN/BLG devices demonstrated in this work allows to readdress the broad field of possible applications offered by BLG, such as diodes [60], phonon-lasers [35,61], hot-electron bolometers [62], fieldeffect transistors (FET) [63][64][65] and tunnel FETs [66]. The latter two are especially interesting for terahertz (THz) detection, where graphene and BLG based devices have already shown promising results [67,68].…”

Review on graphene nanoribbon devices for logic applications

“…AGNRs have been theoretically predicted to have better carrier transport properties than BLG, n-channel Si MOSFETs and InPhigh-electron-mobility transistors (HEMTs) [122,123], particularly when they are used in GNRFETs with ribbon widths around 3-4 nm; however, recent studies have shown that thermal conductivity decreases around three orders of magnitude in GNRs with widths smaller than 10 nm, indicating a direct relation between the width of the GNR and its diffusive thermal conductivity and effective mean free path [124].…”