Atomic-layer-deposited nanostructures for graphene-based nanoelectronics

Abstract

Graphene is a hexagonally bonded sheet of carbon atoms that exhibits superior transport properties with a velocity of ${10}^8\mathrm{cm}∕\mathrm{s}$ and a room-temperature mobility of $>15000{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ . How to grow gate dielectrics on graphene with low defect states is a challenge for graphene-based nanoelectronics. Here, we present the growth behavior of ${\mathrm{Al}}_2{\mathrm{O}}_3$ and $\mathrm{Hf}{\mathrm{O}}_2$ films on highly ordered pyrolytic graphite (HOPG) by atomic layer deposition (ALD). To our surprise, large numbers of ${\mathrm{Al}}_2{\mathrm{O}}_3$ and $\mathrm{Hf}{\mathrm{O}}_2$ nanoribbons, with dimensions of $5–200\mathrm{nm}$ in width and $>50\mu \mathrm{m}$ in length, are observed on HOPG surfaces at growth temperature between 200 and $250°\mathrm{C}$ . This is due to the large numbers of step edges of graphene on HOPG surfaces, which serve as nucleation sites for the ALD process. These ${\mathrm{Al}}_2{\mathrm{O}}_3$ and $\mathrm{Hf}{\mathrm{O}}_2$ nanoribbons can be used as hard masks to generate graphene nanoribbons or as top-gate dielectrics for graphene devices. This methodology could be extended to synthesize insulating, semiconducting, and metallic nanostructures and their combinations.