Atomic-layer-deposited nanostructures for graphene-based nanoelectronics.

Graphene is a hexagonally bonded sheet of carbon atoms that exhibits superior transport properties with a velocity of 10⁸ cm/s and a room-temperature mobility of >15 000 cm²/V 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 Al₂O₃ and HfO₂ films on highly ordered pyrolytic graphite (HOPG) by atomic layer deposition (ALD). To our surprise, large numbers of Al₂O₃ and HfO₂ nanoribbons, with dimensions of 5–200 nm in width and >50 μm in length, are observed on HOPG surfaces at growth temperature between 200 and 250 °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 Al₂O₃ and HfO₂ 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. [ABSTRACT FROM AUTHOR]