Performance projection of graphene nanomesh and nanoroad transistors

We examine the performance limits of field-effect transistors (FETs) with chemically modified graphene as the channel materials. Graphene nanoroad (XNR) and graphene nanomesh (XNM) can be created through selective chemical modification by an X adsorbate (either H or F) on graphene, which generates a bandgap while conserving the continuous two-dimensional (2D) atomistic layer. We adopt a ballistic transistor model, where the band structures were calculated using ab initio simulations to assess the performance of graphene nanoroad and nanomesh transistors. It is shown that arrays of graphene nanoroads, defined by hydrogenation or fluorination of atomically narrow dimer lines in a 2D graphene, are most ideal for transistor channel materials in terms of delivering a large ON-current, and significantly outperform Si metal-oxide-semiconductor field-effect transistors (MOSFETs). Alternatively, comparable performance to silicon can be achieved by careful design of a graphene nanomesh through patterned hydrogenation or fluorination. Both hydrogenation and fluorination lead to similar transistor performance, with fluorination more preferred in terms of chemical energetics.