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Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene

Mona Alyobi, Chris Barnett, Richard Cobley Orcid Logo

Crystals, Volume: 7, Issue: 11, Start page: 349

Swansea University Author: Richard Cobley Orcid Logo

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DOI (Published version): 10.3390/cryst7110349

Abstract

Graphene’s novel electrical, optical, and mechanical properties are affected both by substrate interaction and processing steps required to fabricate contacts and devices. Annealing is used to clean graphene devices, but this can lead to doping and defect changes and strain effects. There is often d...

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Published in: Crystals
ISSN: 2073-4352
Published: 2017
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URI: https://cronfa.swan.ac.uk/Record/cronfa36726
first_indexed 2017-11-13T14:27:15Z
last_indexed 2018-02-09T05:29:20Z
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spelling 2017-12-05T12:56:17.6036177 v2 36726 2017-11-13 Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene 2ce7e1dd9006164425415a35fa452494 0000-0003-4833-8492 Richard Cobley Richard Cobley true false 2017-11-13 ACEM Graphene’s novel electrical, optical, and mechanical properties are affected both by substrate interaction and processing steps required to fabricate contacts and devices. Annealing is used to clean graphene devices, but this can lead to doping and defect changes and strain effects. There is often disagreement about which of these effects are occurring and which result in observed changes in Raman spectra. The effects of vacuum annealing on mechanically exfoliated pristine, suspended, and attached thin and thick few-layer graphene on SiO2/Si are investigated here using scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). Before annealing, Raman shows that the differences in 2D and G band positions and the appearance of a disorder-induced D band of all regions were mainly because of compressive or tensile structural deformations emerging through mechanical exfoliation instead of charge doping. Annealing at low temperature is sufficient to eliminate most of the defects. However, compressive strain is induced in the sheet by annealing at high temperature, and for thin regions increased substrate conformation leads to the apparent disappearance of the sheets. The intensity ratio of the 2D and G bands also reduces with induced compressive strain, and thus should not be used to detect doping. Journal Article Crystals 7 11 349 2073-4352 graphene; annealing; Raman; doping; strain 15 11 2017 2017-11-15 10.3390/cryst7110349 COLLEGE NANME Aerospace, Civil, Electrical, and Mechanical Engineering COLLEGE CODE ACEM Swansea University 2017-12-05T12:56:17.6036177 2017-11-13T10:49:36.6719754 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering Mona Alyobi 1 Chris Barnett 2 Richard Cobley 0000-0003-4833-8492 3 0036726-05122017125605.pdf alyobi2017.pdf 2017-12-05T12:56:05.8270000 Output 1384346 application/pdf Version of Record true 2017-12-05T00:00:00.0000000 false eng
title Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
spellingShingle Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
Richard Cobley
title_short Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
title_full Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
title_fullStr Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
title_full_unstemmed Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
title_sort Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene
author_id_str_mv 2ce7e1dd9006164425415a35fa452494
author_id_fullname_str_mv 2ce7e1dd9006164425415a35fa452494_***_Richard Cobley
author Richard Cobley
author2 Mona Alyobi
Chris Barnett
Richard Cobley
format Journal article
container_title Crystals
container_volume 7
container_issue 11
container_start_page 349
publishDate 2017
institution Swansea University
issn 2073-4352
doi_str_mv 10.3390/cryst7110349
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering
document_store_str 1
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description Graphene’s novel electrical, optical, and mechanical properties are affected both by substrate interaction and processing steps required to fabricate contacts and devices. Annealing is used to clean graphene devices, but this can lead to doping and defect changes and strain effects. There is often disagreement about which of these effects are occurring and which result in observed changes in Raman spectra. The effects of vacuum annealing on mechanically exfoliated pristine, suspended, and attached thin and thick few-layer graphene on SiO2/Si are investigated here using scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). Before annealing, Raman shows that the differences in 2D and G band positions and the appearance of a disorder-induced D band of all regions were mainly because of compressive or tensile structural deformations emerging through mechanical exfoliation instead of charge doping. Annealing at low temperature is sufficient to eliminate most of the defects. However, compressive strain is induced in the sheet by annealing at high temperature, and for thin regions increased substrate conformation leads to the apparent disappearance of the sheets. The intensity ratio of the 2D and G bands also reduces with induced compressive strain, and thus should not be used to detect doping.
published_date 2017-11-15T19:15:54Z
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score 11.1586075

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