Effect of ribbon width on electrical transport properties of graphene nanoribbons

Abstract

There has been growing interest in developing nanoelectronic devices based on graphene because of its superior electrical properties. In particular, patterning graphene into a nanoribbon can open a bandgap that can be tuned by changing the ribbon width, imparting semiconducting properties. In this study, we report the effect of ribbon width on electrical transport properties of graphene nanoribbons (GNRs). Monolayer graphene sheets and Si nanowires (NWs) were prepared by chemical vapor deposition and a combination of nanosphere lithography and metal-assisted electroless etching from a Si wafer, respectively. Back-gated GNR field-effect transistors were fabricated on a heavily p-doped Si substrate coated with a 300 nm-thick SiO2 layer, by O2 reactive ion etching of graphene sheets using etch masks based on Si NWs aligned on the graphene between the two electrodes by a dielectrophoresis method. This resulted in GNRs with various widths in a highly controllable manner, where the on/off current ratio was inversely proportional to ribbon width. The field-effect mobility decreased with decreasing GNR widths due to carrier scattering at the GNR edges. These results demonstrate the formation of a bandgap in GNRs due to enhanced carrier confinement in the transverse direction and edge effects when the GNR width is reduced.

Lithographic band structure engineering of graphene

“…Top-down patterning of graphene on this scale, however, is very challenging without compromising the quasiballistic condition, l e ≥ w, as has been shown for graphene nanoribbons [13,21]. This has led to more than a decade of research into ways of archiving dense nanostructuring of graphene without compromising the transport properties, but so far disorder at edges increasingly dominate transport measurements as pattern densities increase [22][23][24]. Figure 1 summarise a subset of key experimental works [19,20,[25][26][27][28][29][30][31] featuring twodimensional (2D) nanostructured graphene as well as microscale Hall bars for reference [31], with the reported charge carrier mobility, µ, plotted against the minimum feature size of the system.…”

Far-infrared photodetection in graphene nanoribbon heterostructures with black-phosphorus base layers

“…Both the realization of the resonant interband intersubband radiative transitions and the possibility of the pronounced plasmonic oscillations require relatively perfect GNRs with high carrier mobilities along the GNRs or their ballistic transport, which are achievable in real GNR-based heterostructures. The electron and hole mobilities on the order of ð2000 to 2500Þ cm 2 ∕Vs measured in GNRs 43,44 are sufficiently large to support resonant interband transitions and plasmonic oscillations.…”

Charge Focusing and Enhanced Fermi-Level Modulation in Hybrid Graphene Nanospike Organic Thin-Film Transistors

“…The best ratio of the effect is ∼1:3 according to ref . Another constraint is that the width of the graphene nanospike contact cannot be too narrow because the edge damage and traps induced during the fabrication process would influence the charge transport in graphene significantly , and degrade the overall device performance. For a dielectric thickness of 300 nm, the optimal width of the graphene nanospike should be between 200 and 500 nm.…”