Abstract:We report the determination of the thickness of graphene layers by Auger electron spectroscopy (AES). We measure AES spectra of graphenes with different numbers of layers. The AES spectroscopy shows distinct spectrum shape, intensity, and energy characteristics with an increasing number of graphene layers. We also calculate electron inelastic mean free paths for graphene layers directly from these measurements. The method allows unambiguous and high-throughput determination of thickness up to six graphene laye… Show more
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.
“…Recently, we established Auger electron spectroscopy (AES) as a method to characterize the number and structure of graphene layers on arbitrary substrates [58]. We found that AES gives distinct spectrum shape, intensity and energy characteristics with an increasing number of graphene layers ( Figure 2).…”
Section: Auger Electron Characteristics Of Graphene Layersmentioning
Graphene has unique physical properties, and a variety of proof-of-concept devices based on graphene have been demonstated. A prerequisite for the application of graphene is its production in a controlled manner because the number of graphene layers and the defects in these layers significantly influence transport properties. In this paper, we briefly review our recent work on the controlled synthesis of graphene and graphene-based composites, the development of methods to characterize graphene layers, and the use of graphene in clean energy applications and for rapid DNA sequencing. For example, we have used Auger electron spectroscopy to characterize the number and structure of graphene layers, produced single-layer graphene over a whole Ni film substrate, synthesized well-dispersed reduced graphene oxide that was uniformly grafted with unique gold nanodots, and fabricated graphene nanoscrolls. We have also explored applications of graphene in organic solar cells and direct, ultrafast DNA sequencing. Finally, we address the challenges that graphene still face in its synthesis and clean energy and biological sensing applications.
“…of graphene having wafer size typically used in semiconductor industry. If we restrict ourselves only to the measurement of the average thickness of graphene still many methods can be used; a relatively large selection of possible measurements is discussed in ref [1]. Among the known methods Raman spectroscopy is the most applicable one since it a./ can verify the presence of graphene, b./ measures the defects, c./ can be applied to determine the thickness, and as an optical method provides a simple measurement.…”
Section: Introductionmentioning
confidence: 99%
“…It is interesting that Auger electron spectroscopy (AES), the classical surface sensitive analytical tool, has been rarely used in graphene research. The main reason might be that though the shape of the carbon Auger peak of graphene is strongly different from that of various carbides it is only slightly different from the various graphite forms [1]; thus, the identification of graphene is not completely safe by using AES. On the other hand AES [1,4] as well as X-ray photoelectron spectroscopy (XPS) [5] can be readily applied for the determination of thickness of the graphene layer since the transport (attenuation) of medium energy electrons through ad-layers is well known [6].…”
Section: Introductionmentioning
confidence: 99%
“…On the other hand AES [1,4] as well as X-ray photoelectron spectroscopy (XPS) [5] can be readily applied for the determination of thickness of the graphene layer since the transport (attenuation) of medium energy electrons through ad-layers is well known [6]. Xu et al [1] proposed AES as A Rational…”
Auger electron spectroscopy (AES) depth profiling was applied for determination of the thickness of a macroscopic size graphene sheet grown on 2 inch 6H-SiC (0001) by sublimation epitaxy. The measured depth profile deviated from the expected exponential form showing the presence of an additional, buffer layer. The measured depth profile was compared to the simulated one which allowed the derivation of the thicknesses of the graphene and buffer layers and the Si concentration of buffer layer. It has been shown that the C made buffer layer contains about 30% unsaturated Si. The depth profiling was 2 carried out in several points (diameter 50m), which permitted the constructing of a thickness distribution characterizing the uniformity of the graphene sheet.
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