Plasma-enhanced atomic layer deposition of Al$_2$O$_3$ on graphene using monolayer hBN as interfacial layer

TL;DR

This study demonstrates a plasma-enhanced atomic layer deposition method for high-quality Al₂O₃ dielectric on graphene, utilizing a monolayer hBN as a protective interfacial layer to prevent damage and maintain electrical performance.

Contribution

The paper introduces a novel process combining plasma ALD with a monolayer hBN to deposit high-quality Al₂O₃ on graphene without damaging the material.

Findings

Effective protection of graphene with hBN during plasma ALD

Maintained electrical properties of graphene after deposition

High breakdown electric fields indicating high-quality dielectric films

Abstract

The deposition of dielectric materials on graphene is one of the bottlenecks for unlocking the potential of graphene in electronic applications. In this paper we demonstrate the plasma enhanced atomic layer deposition of 10 nm thin high quality Al$_2$O$_3$ on graphene using a monolayer of hBN as protection layer. Raman spectroscopy was 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 was observed without an hBN layer. Electrical characterization of double gated graphene field effect devices confirms that the graphene did not degrade during the plasma deposition of Al$_2$O$_3$. The leakage current densities were consistently below 1 nA/mm for electric fields across the insulators of up to 8 MV/cm, with irreversible breakdown happening above. Such breakdown electric fields are typical for Al$_2$O$_3$ and can be seen as an indicator for high quality dielectric films.