Plasma‐Enhanced Atomic Layer Deposition of Al₂O₃ on Graphene Using Monolayer hBN as Interfacial Layer

Abstract The deposition of dielectric materials on graphene is one of the bottlenecks for unlocking the potential of graphene in electronic applications. The plasma enhanced atomic layer deposition of 10 nm thin high quality aluminum oxide (Al₂O₃) on graphene is demonstrated using a monolayer of hexagonal boron nitride (hBN) as protection layer. Raman spectroscopy is performed to analyze possible structural changes of the graphene lattice caused by the plasma deposition. The results show that a monolayer of hBN in combination with an optimized deposition process can effectively protect graphene from damage, while significant damage is observed without an hBN layer. Electrical characterization of double gated graphene field effect devices confirms that the graphene does not degrade during the plasma deposition of Al₂O₃. The leakage current densities are consistently below 1 pA µm⁻² for electric fields across the insulators of up to 8 MV cm⁻¹, with irreversible breakdown happening above. Such breakdown electric fields are typical for Al₂O₃ and can be seen as an indicator for high quality dielectric films.