Abstract
Graphene has attracted a lot of interest as a potential replacement for silicon in future integrated circuits due to its remarkable electronic and transport properties. In order to meet technology requirements for an acceptable bandgap, graphene needs to be patterned into graphene nanoribbons (GNRs), while one-dimensional (1D) edge metal contacts (MCs) are needed to allow for the encapsulation and preservation of the transport properties. While the properties of GNRs with ideal contacts have been studied extensively, little is known about the electronic and transport properties of GNRs with 1D edge MCs, including contact resistance (RC), which is one of the key device parameters. In this work, we employ atomistic quantum transport simulations of GNRs with MCs modeled with the wide-band limit (WBL) approach to explore their metallization effects and contact resistance. By studying density of states (DOS), transmission and conductance, we find that metallization decreases transmission and conductance, and either enlarges or diminishes the transport gap depending on GNR dimensions. We calculate the intrinsic quantum limit of width-normalized RC and find that the limit depends on GNR dimensions, decreasing with width downscaling to ~21 Ω∙µm in 0.4 nm-wide GNRs, and increasing with length downscaling up to ~196 Ω∙µm in 5 nm-long GNRs. We demonstrate that 1D edge contacts and size engineering can be used to tune the RC in GNRs to values lower than those of graphene.
Highlights
We investigated the impact of attaching wide-band limit (WBL) metal contacts (MCs) on the electronic and transport properties of graphene nanoribbons (GNRs) such as density of states (DOS), transmission, bandgap (EG ) and transport gap (ETG ), conductance, and RC for GNRs of various lengths (L) and widths (W) of interest for the potential complementary MOS (CMOS) technology based on ultra-scaled GNR metal-oxide-semiconductor fieldeffect transistors (MOSFETs)
The metallization-induced DOS increase inside the bandgap is stronger for wider GNRs due to the longer 1D contacts that supply more localized states to the total DOS
As will be shown later, these states are localized in GNR regions that are close to the edge contacts
Summary
While different technology options are being explored to replace silicon FinFETs, such as nanowire FETs based on germanium and III–V semiconductor materials [1,2], the emergence of two-dimensional (2D) materials has instigated a tremendous amount of interest in exploring their applicability for future electronic devices [3]. The main advantages they bring are perfect electrostatic channel control due to atomic-level thickness combined with excellent electronic and transport properties, leading to potentially high driving currents
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