Corrugation of Chemically Converted Graphene Monolayers on SiO2

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• 作者：Alexander Sinitskii ; Dmitry V. Kosynkin ; Ayrat Dimiev ; James M. Tour
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：June 22, 2010
• 年：2010
• 卷：4
• 期：6
• 页码：3095-3102
• 全文大小：494K
• 年卷期：0
• ISSN：1936-086X

文摘

Sheets of chemically converted graphene (CCG) on the surface of Si/SiO₂ substrates exhibit nanoscopic corrugation. This corrugation has been assumed to be caused by a combination of factors including (a) thermal treatments in the device preparation, (b) different oxygen-containing addends on the CCG, and (c) the substrate roughness. In this paper, we study the interplay of these factors in the corrugation behavior of monolayer CCG flakes, prepared by reduction of graphene oxide (GO) synthesized by Hummers method, and CCG nanoribbons, produced by chemical unzipping of carbon nanotubes, followed by the reduction by hydrazine at 95 °C. We have studied the morphology, composition, and electrical properties of the flakes and nanoribbons before and after annealing in Ar/H₂ at 300 °C. Our experiments demonstrate that, despite the temperature treatment and the associated removal of the oxygen-containing addends from the basal plane of the CCG, the corrugation pattern of the CCG exhibits almost no change upon annealing. This suggests that the substrate roughness, not the chemical addends nor the thermal cycling, is the predominant determinant in the graphene corrugation. This conclusion is supported by depositing GO flakes on freshly cleaved mica. Such flakes were shown to have extremely low corrugation (rms ∼70 pm), as dictated by the atomically flat surface of mica. Our experimental observations are in accord with the results of our molecular dynamics simulations, which show that interaction with the substrate greatly suppresses the intrinsic corrugation of graphene materials.