Aluminum oxide nucleation in the early stages of atomic layer deposition on epitaxial graphene

Abstract

In this work, the nucleation and growth mechanism of aluminum oxide (Al2O3) in the early stages of the direct atomic layer deposition (ALD) on monolayer epitaxial graphene (EG) on silicon carbide (4H-SiC) has been investigated by atomic force microscopy (AFM) and Raman spectroscopy. Contrary to what is typically observed for other types of graphene, a large and uniform density of nucleation sites was observed in the case of EG and ascribed to the presence of the buffer layer at EG/SiC interface. The deposition process was characterized by Al2O3 island growth in the very early stages, followed by the formation of a continuous Al2O3 film (2.4 nm thick) after only 40 ALD cycles due to the islands coalescence, and subsequent layer-by-layer growth. Raman spectroscopy analyses showed low impact of the ALD process on the defects density and doping of EG. The EG strain was also almost unaffected by the deposition in the regime of island growth and coalescence, whereas a significant increase was observed after the formation of a compact Al2O3 film. The obtained results can have important implications for device applications of epitaxial graphene requiring the integration of ultra-thin high-k insulators.

19 pages, 6 figures

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• Electrochemically Top Gated Graphene: Monitoring Dopants by Raman Scattering
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• Substrate-assisted nucleation of ultra-thin dielectric layers on graphene by atomic layer deposition
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Cited by in corpus (5)

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• Plasma-enhanced atomic layer deposition of Al${}_2$O${}_3$ on graphene using monolayer hBN as interfacial layer
• Atomic Layer Deposition Nucleation Dependence on Diamond Surface Termination
• Direct atomic layer deposition of ultrathin aluminium oxide on monolayer $Mo{S}_2$ exfoliated on gold: the role of the substrate