Nanomaterials (Jun 2023)

Plasma-Induced Surface Modification of Sapphire and Its Influence on Graphene Grown by Plasma-Enhanced Chemical Vapour Deposition

  • Miguel Sinusia Lozano,
  • Ignacio Bernat-Montoya,
  • Todora Ivanova Angelova,
  • Alberto Boscá Mojena,
  • Francisco J. Díaz-Fernández,
  • Miroslavna Kovylina,
  • Alejandro Martínez,
  • Elena Pinilla Cienfuegos,
  • Víctor J. Gómez

DOI
https://doi.org/10.3390/nano13131952
Journal volume & issue
Vol. 13, no. 13
p. 1952

Abstract

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In this work, we study the influence of the different surface terminations of c-plane sapphire substrates on the synthesis of graphene via plasma-enhanced chemical vapor deposition. The different terminations of the sapphire surface are controlled by a plasma process. A design of experiments procedure was carried out to evaluate the major effects governing the plasma process of four different parameters: i.e., discharge power, time, pressure and gas employed. In the characterization of the substrate, two sapphire surface terminations were identified and characterized by means of contact angle measurements, being a hydrophilic (hydrophobic) surface and the fingerprint of an Al- (OH-) terminated surface, respectively. The defects within the synthesized graphene were analyzed by Raman spectroscopy. Notably, we found that the ID/IG ratio decreases for graphene grown on OH-terminated surfaces. Furthermore, two different regimes related to the nature of graphene defects were identified and, depending on the sapphire terminated surface, are bound either to vacancy or boundary-like defects. Finally, studying the density of defects and the crystallite area, as well as their relationship with the sapphire surface termination, paves the way for increasing the crystallinity of the synthesized graphene.

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