Quantum Transport Analysis of Conductance Variability in Graphene Nanoribbons With Edge Defects

Abstract

We study the influence of edge defects and the downscaling of graphene nanoribbon (GNR) width ( $W$ ) on the ON- and OFF-state conductance ( $G_{\mathrm{\scriptscriptstyle ON}}$ and $G_{\mathrm{\scriptscriptstyle OFF}})$ and the ON–OFF conductance ratio ( $G_{\mathrm{\scriptscriptstyle ON}}/G_{\mathrm{\scriptscriptstyle OFF}})$ . The averaged properties and the variability are explored by simulating ensembles of defected GNRs with various percentages of edge defects using atomistic quantum transport simulations. We find that even 10% edge defects decrease $G_{\mathrm{\scriptscriptstyle ON}}$ by at least 40%, even in the widest simulated GNRs, and that $G_{\mathrm{\scriptscriptstyle ON}}$ scales as $\sim {W} ^{2}$ for $W > 3.2$ nm and $\sim {W} ^{9}$ for $W nm. The relative variability of $G_{\mathrm{\scriptscriptstyle ON}}$ ( $3\sigma $ compared with average) increases from $\sim 30$ % to $\sim 1000$ % when the width is scaled from 4.8 to 1.1 nm. Furthermore, while its variability can reach orders of magnitude, we find that there exists the optimum nanoribbon width range between 1.8 and 3.3 nm in terms of $G_{\mathrm{\scriptscriptstyle ON}}/G_{\mathrm{\scriptscriptstyle OFF}}$ in GNRs with edge defects.