Low-temperature synthesis of vertically aligned graphene through microwave-assisted chemical vapour deposition

Kulczyk-Malecka, J ORCID: https://orcid.org/0000-0002-4905-3635, Santos, IVJD, Betbeder, M, Rowley-Neale, SJ, Gao, Z and Kelly, PJ (2021) Low-temperature synthesis of vertically aligned graphene through microwave-assisted chemical vapour deposition. Thin Solid Films, 733. p. 138801. ISSN 0040-6090

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Abstract

The intrinsic properties of vertically aligned graphene (VG), such as a high ratio of exposed active edge sites compared to inert basal sites, non-stacking morphology and large surface-to-volume ratio make it applicable to numerous advanced technologies such as sensors, flexible electronics and fuel cells. Plasma-enhanced chemical vapour deposition has emerged as a promising technique to synthesise graphene at lower temperatures than a conventional chemical vapour deposition (CVD) process, providing a better control over the deposition parameters to tailor graphene properties. This study presents a cost effective, scalable, single step synthesis of a high quality VG at low temperatures. The samples were synthesised in a microwave (MW) assisted CVD reactor, which allowed for the decomposition of CH4 and H2 gas mixtures in Ar as a carrier gas, and VG growth directly onto Si wafer substrates without any additional heat applied to the substrate. Deposition conditions, such as MW power, gas ratio, and substrate-to-plasma separation were optimized to tailor the morphology, growth rate and electrochemical performance of the VG. The physiochemical analysis revealed that the fabricated VG consisted of high quality vertically aligned sp2 graphene, whilst a cyclic voltammetry analysis confirmed that the structures are electrochemically active and demonstrate a typical characteristics of quasi-reversible processes.