No Cover Image

E-Thesis 603 views 270 downloads

Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene / MASHAEL ALSHAIKH

Swansea University Author: MASHAEL ALSHAIKH

  • Alshaikh_Mashael_M_PhD_Thesis_Final_Redacted.pdf

    PDF | Redacted version - open access

    Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene © 2021 by Mashael M. Alshaikh is licensed under a Creative Commons Attribution (CC-BY) License.

    Download (17.09MB)

DOI (Published version): 10.23889/SUthesis.59109

Abstract

Silicon dioxide (SiO2) is a common support for studying two-dimensional materials and creating devices from them. However, graphene conformation to SiO2 roughness worsens the electronic properties, whereas graphene deposited on flat terraces of insulating mica is free of ripples. This thesis solves...

Full description

Published: Swansea 2022
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Cobley, Richard
URI: https://cronfa.swan.ac.uk/Record/cronfa59109
Tags: Add Tag
No Tags, Be the first to tag this record!
first_indexed 2022-01-07T10:40:47Z
last_indexed 2022-01-08T04:28:06Z
id cronfa59109
recordtype RisThesis
fullrecord <?xml version="1.0"?><rfc1807><datestamp>2022-01-07T10:53:05.1096533</datestamp><bib-version>v2</bib-version><id>59109</id><entry>2022-01-07</entry><title>Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene</title><swanseaauthors><author><sid>894f46d19a7779c42936d145631805da</sid><firstname>MASHAEL</firstname><surname>ALSHAIKH</surname><name>MASHAEL ALSHAIKH</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2022-01-07</date><abstract>Silicon dioxide (SiO2) is a common support for studying two-dimensional materials and creating devices from them. However, graphene conformation to SiO2 roughness worsens the electronic properties, whereas graphene deposited on flat terraces of insulating mica is free of ripples. This thesis solves key challenges in the use of mica to support mechanically exfoliated graphene. Methods of mica cleavage and graphene exfoliation, and settings for electron microscopy, atomic force microscopy (AFM) and Raman spectroscopy were developed. Vacuum annealing was compared for graphene samples of different thicknesses, down to a single layer. Pre- and post-annealing, graphene on mica provided defect-free graphene and no observable strain or doping. In contrast, graphene on SiO2 showed disorder before annealing. Annealing up to 300&#xB0;C reduced the Raman defect peak but did not remove it. Above 300&#xB0;C, the defect peak increased. Graphene on SiO2 appeared to become &#x2018;invisible&#x2019; with AFM after annealing at 500&#xB0;C, in line with previous observations with scanning electron microscopy. Other studies attributed this to the graphene being removed, but, here, using substrate markers, Raman spectroscopy and line-averaged AFM showed that the graphene was still present but had conformed to the underlying roughness of the SiO2 so well as to appear nearly invisible. Mica annealed at 400&#xB0;C showed the formation of potassium carbonate particles following dehydroxylation of the mica surface at a temperature lower than previously reported. In addition, the graphene appeared to act as a mask, protecting the mica underneath it while the surrounding surface was removed at 500&#xB0;C. Patterning and etching mica are essential to create location grids and etch trenches to suspend deposited materials. The first patterning lithography recipe for mica was established herein using electron-beam lithography. Finally, mechanically exfoliated graphene was successfully transferred to the patterned mica and studied.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords>Graphene, Mica, Silicon dioxide, roughness, lithography, annealing</keywords><publishedDay>7</publishedDay><publishedMonth>1</publishedMonth><publishedYear>2022</publishedYear><publishedDate>2022-01-07</publishedDate><doi>10.23889/SUthesis.59109</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions.</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Cobley, Richard</supervisor><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>Saudi Government (Scholarship)</degreesponsorsfunders><apcterm/><lastEdited>2022-01-07T10:53:05.1096533</lastEdited><Created>2022-01-07T10:19:12.1392440</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>MASHAEL</firstname><surname>ALSHAIKH</surname><order>1</order></author></authors><documents><document><filename>59109__22068__405aa54acb6441c38b3159264368393e.pdf</filename><originalFilename>Alshaikh_Mashael_M_PhD_Thesis_Final_Redacted.pdf</originalFilename><uploaded>2022-01-07T10:44:14.9185401</uploaded><type>Output</type><contentLength>17921061</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><documentNotes>Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene &#xA9; 2021 by Mashael M. Alshaikh is licensed under a Creative Commons Attribution (CC-BY) License.</documentNotes><copyrightCorrect>true</copyrightCorrect><language>eng</language><licence>https://creativecommons.org/licenses/by/4.0/</licence></document></documents><OutputDurs/></rfc1807>
spelling 2022-01-07T10:53:05.1096533 v2 59109 2022-01-07 Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene 894f46d19a7779c42936d145631805da MASHAEL ALSHAIKH MASHAEL ALSHAIKH true false 2022-01-07 Silicon dioxide (SiO2) is a common support for studying two-dimensional materials and creating devices from them. However, graphene conformation to SiO2 roughness worsens the electronic properties, whereas graphene deposited on flat terraces of insulating mica is free of ripples. This thesis solves key challenges in the use of mica to support mechanically exfoliated graphene. Methods of mica cleavage and graphene exfoliation, and settings for electron microscopy, atomic force microscopy (AFM) and Raman spectroscopy were developed. Vacuum annealing was compared for graphene samples of different thicknesses, down to a single layer. Pre- and post-annealing, graphene on mica provided defect-free graphene and no observable strain or doping. In contrast, graphene on SiO2 showed disorder before annealing. Annealing up to 300°C reduced the Raman defect peak but did not remove it. Above 300°C, the defect peak increased. Graphene on SiO2 appeared to become ‘invisible’ with AFM after annealing at 500°C, in line with previous observations with scanning electron microscopy. Other studies attributed this to the graphene being removed, but, here, using substrate markers, Raman spectroscopy and line-averaged AFM showed that the graphene was still present but had conformed to the underlying roughness of the SiO2 so well as to appear nearly invisible. Mica annealed at 400°C showed the formation of potassium carbonate particles following dehydroxylation of the mica surface at a temperature lower than previously reported. In addition, the graphene appeared to act as a mask, protecting the mica underneath it while the surrounding surface was removed at 500°C. Patterning and etching mica are essential to create location grids and etch trenches to suspend deposited materials. The first patterning lithography recipe for mica was established herein using electron-beam lithography. Finally, mechanically exfoliated graphene was successfully transferred to the patterned mica and studied. E-Thesis Swansea Graphene, Mica, Silicon dioxide, roughness, lithography, annealing 7 1 2022 2022-01-07 10.23889/SUthesis.59109 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions. COLLEGE NANME COLLEGE CODE Swansea University Cobley, Richard Doctoral Ph.D Saudi Government (Scholarship) 2022-01-07T10:53:05.1096533 2022-01-07T10:19:12.1392440 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised MASHAEL ALSHAIKH 1 59109__22068__405aa54acb6441c38b3159264368393e.pdf Alshaikh_Mashael_M_PhD_Thesis_Final_Redacted.pdf 2022-01-07T10:44:14.9185401 Output 17921061 application/pdf Redacted version - open access true Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene © 2021 by Mashael M. Alshaikh is licensed under a Creative Commons Attribution (CC-BY) License. true eng https://creativecommons.org/licenses/by/4.0/
title Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
spellingShingle Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
MASHAEL ALSHAIKH
title_short Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
title_full Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
title_fullStr Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
title_full_unstemmed Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
title_sort Mica as an Ultra-Flat Substrate for Studying Mechanically Exfoliated Graphene
author_id_str_mv 894f46d19a7779c42936d145631805da
author_id_fullname_str_mv 894f46d19a7779c42936d145631805da_***_MASHAEL ALSHAIKH
author MASHAEL ALSHAIKH
author2 MASHAEL ALSHAIKH
format E-Thesis
publishDate 2022
institution Swansea University
doi_str_mv 10.23889/SUthesis.59109
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 Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description Silicon dioxide (SiO2) is a common support for studying two-dimensional materials and creating devices from them. However, graphene conformation to SiO2 roughness worsens the electronic properties, whereas graphene deposited on flat terraces of insulating mica is free of ripples. This thesis solves key challenges in the use of mica to support mechanically exfoliated graphene. Methods of mica cleavage and graphene exfoliation, and settings for electron microscopy, atomic force microscopy (AFM) and Raman spectroscopy were developed. Vacuum annealing was compared for graphene samples of different thicknesses, down to a single layer. Pre- and post-annealing, graphene on mica provided defect-free graphene and no observable strain or doping. In contrast, graphene on SiO2 showed disorder before annealing. Annealing up to 300°C reduced the Raman defect peak but did not remove it. Above 300°C, the defect peak increased. Graphene on SiO2 appeared to become ‘invisible’ with AFM after annealing at 500°C, in line with previous observations with scanning electron microscopy. Other studies attributed this to the graphene being removed, but, here, using substrate markers, Raman spectroscopy and line-averaged AFM showed that the graphene was still present but had conformed to the underlying roughness of the SiO2 so well as to appear nearly invisible. Mica annealed at 400°C showed the formation of potassium carbonate particles following dehydroxylation of the mica surface at a temperature lower than previously reported. In addition, the graphene appeared to act as a mask, protecting the mica underneath it while the surrounding surface was removed at 500°C. Patterning and etching mica are essential to create location grids and etch trenches to suspend deposited materials. The first patterning lithography recipe for mica was established herein using electron-beam lithography. Finally, mechanically exfoliated graphene was successfully transferred to the patterned mica and studied.
published_date 2022-01-07T04:16:09Z
_version_ 1763754083451142144
score 11.016503

Similar Items