In-situ thermal Raman spectroscopy of single-layer graphene on different substrates
Résumé
In this study, we discovered through Raman spectroscopy that single-layered graphene is not destroyed at 600 °C generally but the decomposition temperature depends linearly on the coefficient of thermal expansion (CTE) of the substrate. Moreover, we showed that there is a different phenomenon behind the decomposition of graphene in air and in vacuum. While in both environments, decomposition is initiated by the prolongation of the C-C bonds, in air the increased strain raises the graphene reactivity with oxygen, therefore it is the oxygen which destroys graphene whereas in a vacuum the strain alone causes the decomposition. The maximal strain for the single-layered graphene was measured for both environments. The experiments were carried out on 8 different substrates with very different CTEs. We also calculated the Raman shift thermal coefficient for graphene on Si, Pt, Au, and Cu and discussed the changes in graphene through the very wide temperature changes (−196 to 600 °C).