Armchair Graphene Nanoribbons Grown Directly on Germanium with High Conductance and On/Off Ratio

The chemical vapor deposition of graphene on Ge(001) can result in highly anisotropic crystal growth, enabling the facile synthesis of oriented, quasi-one-dimensional, graphene nanoribbons that are semiconducting, whereas continuous two-dimensional graphene is semimetallic. This bottom-up synthesis yields sub-10 nm ribbons with predominately smooth armchair edges, and overcomes long-standing challenges that have limited top-down ribbon fabrication (e.g., poor resolution and disordered ribbon edges). Here, we characterize the charge transport properties of nanoribbons with sub-10 nm widths grown on Ge(001). We show that nanoribbons synthesized via this technique can simultaneously achieve high on-state conductance of 5 μS and high on/off conductance ratio of 2×10⁴ in field-effect transistors, favorably comparing to or exceeding the performance of ribbons fabricated by other approaches. These charge transport measurements demonstrate that if the positioning and width uniformity of the ribbons are improved, for example via the use of nanoscale seeds to template growth, the direct synthesis of nanoribbons on Ge(001) could provide a scalable route toward the practical realization of high-performance semiconducting graphene technologies.