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. 2021 Jun 30;14(13):3670.
doi: 10.3390/ma14133670.

Metallization-Induced Quantum Limits of Contact Resistance in Graphene Nanoribbons with One-Dimensional Contacts

Mirko Poljak  1 , Mislav Matić  1
Affiliations

Metallization-Induced Quantum Limits of Contact Resistance in Graphene Nanoribbons with One-Dimensional Contacts

Mirko Poljak et al. Materials (Basel). .

Erratum in

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.

Keywords: NEGF; contact resistance; edge contact; graphene nanoribbon; metallization; one-dimensional contact; quantum transport.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Illustration of the system under study. A graphene nanoribbon is attached to a 1D edge contact that is described with broadening and self-energy within the WBL approximation.
Figure 2
Figure 2
(a) Density of states in GNRs with MCs, for various widths; (b) impact of width scaling on the transmission of GNRs with MCs; (c) band and transport gaps in GNRs with ICs and MCs, respectively. In all cases, L = 15.2 nm.
Figure 3
Figure 3
(a) Width-dependent transmission in GNRs with ICs and MCs. Impact of GNR width downscaling on (b) ON-state conductance, (c) contact resistance, and (d) width-normalized contact resistance. In all cases, L = 15.2 nm.
Figure 4
Figure 4
Influence of length downscaling from 15.2 nm to 5.0 nm on (a) density of states, (b) transmission, and (c) the transport gap in GNRs with MCs. In all plots, corresponding results for the IC case are inserted for comparison. W = 2.6 nm.
Figure 5
Figure 5
Local density of states in 2.6 nm-wide GNRs with 1D edge contacts for different GNR lengths: (a) 10.1 nm, (b) 7.5 nm, and (c) 5.0 nm.
Figure 6
Figure 6
(a) Length-dependent transmission in GNRs with ICs and MCs. Impact of length scaling on (b) ON-state conductance, (c) contact resistance, and (d) width-normalized contact resistance. In all cases, W = 2.6 nm.
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