Enhanced Nucleation of High-k Dielectrics on Graphene by Atomic Layer Deposition

Graphene has emerged as a promising 2-dimensional (2D) material composed of a monolayer of carbon atoms, which is expected to be utilized for nano- and optoelectronic device applications. In order to fabricate high speed graphene transistors with low power consumption, the growth of insulating thin films with high dielectric constant (high-k) on graphene is essential. Atomic layer deposition (ALD) is one of the best deposition techniques to grow functional thin films, however, it is extremely challenging to grow high-k thin films on graphene by ALD because of the lack of surface functional groups (such as hydroxyl groups) on graphene. Here, we demonstrate that the graphene surface is fully covered by Al 2 O 3 thin films (10–30 nm), with significantly reduced leakage current (decreased by a factor of ∼10 7 ), through simple surface treatment of the graphene in the ALD chamber prior to the deposition of the Al 2 O 3 layer by ALD to provide surface nucleation sites on the graphene, without breaking vacuum and changing entire process temperature (100 °C). Physisorbed nuclei were created on the graphene as a form of Al 2 O 3 with the surface treatment using trimethylaluminum (TMA) and H 2 O that are typical ALD precursors for Al 2 O 3 growth. Negligible defects were generated during the graphene surface treatment, which provides promising opportunities in graphene electronics.