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

• Published in: Advanced materials technologies Vol. 6; no. 11
• Main Authors: Canto, Bárbara, Otto, Martin, Powell, Michael J., Babenko, Vitaliy, O'Mahony, Aileen, Knoops, Harm C. M., Sundaram, Ravi S., Hofmann, Stephan, Lemme, Max C., Neumaier, Daniel
• Format: Journal Article
• Language: English
• Published: 01.11.2021
• Subjects: Al 2O 3 thin film; ALD; breakdown field; double‐gate‐transistors; GFET; graphene; hexagonal boron nitride
• ISSN: 2365-709X; 2365-709X
• DOI: 10.1002/admt.202100489

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. The deposition of aluminum oxide (Al2O3) by plasma enhanced atomic layer deposition on graphene protected by a monolayer of hexagonal boron nitride (hBN) is investigated. Raman spectroscopy shows that the graphene is protected from plasma damage. Top‐gated devices fabricated with thin Al2O3 films on hBN/graphene exhibit consistently low leakage currents below 1 pA μm‐2 and high breakdown voltages.