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Anisotropic etching of graphite and graphene in a remote hydrogen plasma

Hug, Dorothee and Zihlmann, Simon and Rehmann, Mirko K. and Kalyoncu, Yemliha B. and Camenzind, Timothy N. and Marot, Laurent and Watanabe, K. and Taniguchi, T. and Zumbühl, Dominik M.. (2017) Anisotropic etching of graphite and graphene in a remote hydrogen plasma. npj 2D Materials and Applications, 1. p. 21.

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Official URL: https://edoc.unibas.ch/60894/

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Abstract

We investigate the etching of a pure hydrogen plasma on graphite samples and graphene flakes on SiO2 and hexagonal boron-nitride substrates. The pressure and distance dependence of the graphite exposure experiments reveals the existence of two distinct plasma regimes: the direct and the remote plasma regime. Graphite surfaces exposed directly to the hydrogen plasma exhibit numerous etch pits of various size and depth, indicating continuous defect creation throughout the etching process. In contrast, anisotropic etching forming regular and symmetric hexagons starting only from preexisting defects and edges is seen in the remote plasma regime, where the sample is located downstream, outside of the glowing plasma. This regime is possible in a narrow window of parameters where essentially all ions have already recombined, yet a flux of H-radicals performing anisotropic etching is still present. At the required process pressures, the radicals can recombine only on surfaces, not in the gas itself. Thus, the tube material needs to exhibit a sufficiently low H radical recombination coefficient, such as found for quartz or pyrex. In the remote regime, we investigate the etching of single layer and bilayer graphene on SiO2 and hexagonal boron-nitride substrates. We find isotropic etching for single layer graphene on SiO2, whereas we observe highly anisotropic etching for graphene on a hexagonal boron-nitride substrate. For bilayer graphene, anisotropic etching is observed on both substrates. Finally, we demonstrate the use of artificial defects to create well defined graphene nanostructures with clean crystallographic edges.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentalphysik Quantenphysik (Zumbühl)
UniBasel Contributors:Zumbühl, Dominik M
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Nature Publishing Group
e-ISSN:2397-7132
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:28 Feb 2018 13:58
Deposited On:28 Feb 2018 13:57

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