Clean graphene surface through high temperature annealing

Xie, Wenjing; Weng, Lu‐Tao; Ng, Kai Mo; Chan, Chak Keung

doi:10.1016/j.carbon.2015.07.046

Cited by 87 publications

(59 citation statements)

References 36 publications

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“…All of the spectra were obtained at 500°C to avoid any hydrocarbon adsorption, and the pressure inside the chamber during the experiment was kept to approximately 10 −8 Torr. The fitted curve of the C1s spectrum of the HOPG after annealing at 500°C for 2 hours was used as a reference spectrum for a defect‐free HOPG surface with only delocalized sp 2 carbons . An asymmetric fitting function combining Doniach‐Sunjic and Gaussian‐Lorentzian functions was used in the curve‐fitting analysis of the C1s spectrum of the HOPG to determine the asymmetry parameter, which was determined to be 0.035.…”

Section: Methodsmentioning

confidence: 99%

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Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Xie

Weng

Yeung

et al. 2018

Surface & Interface Analysis

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Defects were created on the surface of highly oriented pyrolytic graphite (HOPG) by sputtering with an Ar+ ion beam, then characterized using X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) at 500°C. In the XPS C1s spectrum of the sputtered HOPG, a sp3 carbon peak appeared at 285.3 eV, representing surface defects. In addition, 2 sets of peaks, the Cx− and CxH− ion series (where x = 1, 2, 3...), were identified in the ToF‐SIMS negative ion spectrum. In the positive ion spectrum, a series of CxH2+• ions indicating defects was observed. Annealing of the sputtered samples under Ar was conducted at different temperatures. The XPS and ToF‐SIMS spectra of the sputtered HOPG after 800°C annealing were observed to be similar to the spectra of the fresh HOPG. The sp3 carbon peak had disappeared from the C1s spectrum, and the normalized intensities of the CxH− and CxH2+• ions had decreased. These results indicate that defects created by sputtering on the surface of HOPG can be repaired by high‐temperature annealing.

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Section: Methodsmentioning

confidence: 99%

“…The fitted curve of the C1s spectrum of the HOPG after annealing at 500°C for 2 hours was used as a reference spectrum for a defect-free HOPG surface with only delocalized sp 2 carbons. 36 Positive and negative ion spectra were collected at 500°C. The pressure inside the chamber during the experiment was approximately 10 −8 Torr.…”

Section: Xpsmentioning

confidence: 99%

Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Xie

Weng

Yeung

et al. 2018

Surface & Interface Analysis

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“…To remove these residues, graphene is annealed in an H 2 /Ar atmosphere, which causes the PMMA residues to decompose [89]. However, multiple studies have shown that PMMA residues and metal oxide particles from the metal substrate are left on graphene after transfer and subsequent annealing [79,81,87,90,91,92]. This is illustrated in Figure 2.7, which show a Scanning Transmission Electron Microscopy (STEM) High-Angle Annular Dark Field (HAADF) image (STEM HAADF is described in Section 4.2.2) of a transferred graphene sheet.…”

Section: Transfer Of Graphenementioning

confidence: 99%

“…Therefore the reports on PMMA decomposition through annealing of graphene varies [90,92,98]. The process starts at either 160…”

Section: High Temperature Annealingmentioning

confidence: 99%

Transmission Electron Microscopy of 2D Materials: Structure and Surface Properties

Karlsson¹

2016

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Linköping 2016Cover: Multiple stacked Ti 3 C 2 T x MXene sheets imaged by low-voltage, monochromated, aberration-corrected transmission electron microscopy.During the course of research underlying this thesis, Linda Karlsson was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden.c Linda Karlsson, unless stated otherwise Printed by LiU-Tryck 2016 I rarely end up where I was intending to go, but often I end up somewhere I needed to be. -Douglas Adams The Long Dark Tea-Time of The Soul AbstractDuring recent years, new types of materials have been discovered with unique properties. One family of such materials are two-dimensional materials, which include graphene and MXene. These materials are stronger, more flexible, and have higher conductivity than other materials. As such they are highly interesting for new applications, e.g. specialized in vivo drug delivery systems, hydrogen storage, or as replacements of common materials in e.g. batteries, bulletproof clothing, and sensors. The list of potential applications is long for these new materials.As these materials are almost entirely made up of surfaces, their properties are strongly influenced by interaction between their surfaces, as well as with molecules or adatoms attached to the surfaces (surface groups). This interaction can change the materials and their properties, and it is therefore imperative to understand the underlying mechanisms. Surface groups on two-dimensional materials can be studied by Transmission Electron Microscopy (TEM), where high energy electrons are transmitted through a sample and the resulting image is recorded. However, the high energy needed to get enough resolution to observe single atoms damages the sample and limits the type of materials which can be analyzed. Lowering the electron energy decreases the damage, but the image resolution at such conditions is severely limited by inherent imperfections (aberrations) in the TEM. During the last years, new TEM models have been developed which employ a low acceleration voltage together with aberration correction, enabling imaging at the atomic scale without damaging the samples. These aberration-corrected TEMs are important tools in understanding the structure and chemistry of two-dimensional materials.In this thesis the two-dimensional materials graphene and Ti 3 C 2 T x MXene have been investigated by low-voltage, aberration-corrected (scanning) TEM. High temperature annealing of graphene covered by residues from the synthesis is studied, as well as the structure and surface groups on single and double Ti 3 C 2 T x MXene. These results are important contributions to the understanding of this class of materials and how their properties can be controlled. Populärvetenskaplig sammanfattningTvådimensionella material har unika egenskaper som beror på deras speciella struktur. De lämpar sig därmed väl för framtidens elektronik som kräver dels kontroll ner på atomnivå och dels atomärt tunna material. Jag har undersökt dessa egenskaper med Linköping...

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“…However, polymer residues can be avoided by using shadow masks or metal masks directly deposited on graphene during fabrication [34][35][36][37]. Alternatively, resist residues and other common contaminants of the surface can be removed using scalable methods such as high temperature annealing [38].…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability of Epitaxial Graphene Electrodes for Conductive Polymer Nanofiber Devices

Kim

Lara‐Avila

et al. 2017

Crystals

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Abstract:We used large area, monolayer graphene epitaxially grown on SiC (0001) as contact electrodes for polymer nanofiber devices. Our fabrication process, which avoids polymer resist residues on the graphene surface, results in graphene-polyaniline nanofiber devices with Ohmic contacts and electrical conductivity comparable to that of Au-nanofiber devices. We further checked the thermal stability of the graphene contacts to polyaniline devices by annealing up to T = 800 • C, the temperature at which polyaniline nanofibers are carbonized but the graphene electrode remains intact. The thermal stability and Ohmic contact of polymer nanofibers are demonstrated here, which together with the chemical stability and atomic flatness of graphene, make epitaxial graphene on SiC an attractive contact material for future all-carbon electronic devices.

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Clean graphene surface through high temperature annealing

Cited by 87 publications

References 36 publications

Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Transmission Electron Microscopy of 2D Materials: Structure and Surface Properties

Thermal Stability of Epitaxial Graphene Electrodes for Conductive Polymer Nanofiber Devices

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Clean graphene surface through high temperature annealing

Cited by 87 publications

References 36 publications

Repair of defects created by Ar+ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Repair of defects created by Ar+ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Transmission Electron Microscopy of 2D Materials: Structure and Surface Properties

Thermal Stability of Epitaxial Graphene Electrodes for Conductive Polymer Nanofiber Devices

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Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Repair of defects created by Ar⁺ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS