Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect
A chemical vapor deposition method has been proven to produce large scale monolayer graphene. However, it is often reported that such graphene contains a varying amount of defects. In this work, methane precursors of different purities [99.99% (4-9G), 99.90% (3-9G), and 98.90% (2-9G)] were used. It...
Saved in:
Main Authors: | , , , , , , , , |
---|---|
Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2020
|
Subjects: | |
Online Access: | https://hdl.handle.net/10356/142971 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Institution: | Nanyang Technological University |
Language: | English |
id |
sg-ntu-dr.10356-142971 |
---|---|
record_format |
dspace |
spelling |
sg-ntu-dr.10356-1429712020-07-16T08:47:30Z Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect Shiau, Li Lynn Goh, Simon Chun Kiat Wang, Xingli Zhu, MinMin Sahoo, Mamina Tan, Chuan Seng Lai, Chao-Sung Liu, Zheng Tay, Beng Kang School of Electrical and Electronic Engineering School of Materials Science and Engineering Engineering::Electrical and electronic engineering Chemical Vapor Deposition Defects A chemical vapor deposition method has been proven to produce large scale monolayer graphene. However, it is often reported that such graphene contains a varying amount of defects. In this work, methane precursors of different purities [99.99% (4-9G), 99.90% (3-9G), and 98.90% (2-9G)] were used. It is shown that the introduction of defects occurs during graphene growth. It has been attributed to the presence of trace oxygen molecules in the gas precursors. By controlling the amount of oxygen present, one is able to tune the defect density in graphene at will. It is purported that the oxygen reacts with methane to yield methanol and formaldehyde. The latter is oxidized to formic acid. As the graphene network expands, the alcohol and formic acid are incorporated as C - O and O - C=O functional groups. In turn, the graphene experiences an overall global tensile strain due to local bond distortion induced by the electronegative oxygen containing groups. Furthermore, the presence of N2 molecules impedes the proper coalescing of carbon-containing molecules for the formation of the sp2-rich carbon network. Electrical measurement conducted suggests that a high purity precursor (4-9G) induces the least amount of defects, which confers a high Seebeck coefficient (105.1 μV/K) and a low sheet resistance (58.3 ω). In the case of a larger volume of oxygen in the precursor, electrical performance decreases generally. ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) EDB (Economic Devt. Board, S’pore) Published version 2020-07-16T08:47:30Z 2020-07-16T08:47:30Z 2020 Journal Article Shiau, L. L., Goh, S. C. K., Wang, X., Zhu, M., Sahoo, M., Tan, C. S., ... Tay, B. K. (2020). Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect. AIP Advances, 10(4), 045016. doi:10.1063/1.5142310 2158-3226 https://hdl.handle.net/10356/142971 10.1063/1.5142310 2-s2.0-85083630357 4 10 045016 en MOE2015-T2-2-043 MoE Tier 1 2017-1-002-200 A18A4b0055 AIP Advances © 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). application/pdf |
institution |
Nanyang Technological University |
building |
NTU Library |
country |
Singapore |
collection |
DR-NTU |
language |
English |
topic |
Engineering::Electrical and electronic engineering Chemical Vapor Deposition Defects |
spellingShingle |
Engineering::Electrical and electronic engineering Chemical Vapor Deposition Defects Shiau, Li Lynn Goh, Simon Chun Kiat Wang, Xingli Zhu, MinMin Sahoo, Mamina Tan, Chuan Seng Lai, Chao-Sung Liu, Zheng Tay, Beng Kang Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
description |
A chemical vapor deposition method has been proven to produce large scale monolayer graphene. However, it is often reported that such graphene contains a varying amount of defects. In this work, methane precursors of different purities [99.99% (4-9G), 99.90% (3-9G), and 98.90% (2-9G)] were used. It is shown that the introduction of defects occurs during graphene growth. It has been attributed to the presence of trace oxygen molecules in the gas precursors. By controlling the amount of oxygen present, one is able to tune the defect density in graphene at will. It is purported that the oxygen reacts with methane to yield methanol and formaldehyde. The latter is oxidized to formic acid. As the graphene network expands, the alcohol and formic acid are incorporated as C - O and O - C=O functional groups. In turn, the graphene experiences an overall global tensile strain due to local bond distortion induced by the electronegative oxygen containing groups. Furthermore, the presence of N2 molecules impedes the proper coalescing of carbon-containing molecules for the formation of the sp2-rich carbon network. Electrical measurement conducted suggests that a high purity precursor (4-9G) induces the least amount of defects, which confers a high Seebeck coefficient (105.1 μV/K) and a low sheet resistance (58.3 ω). In the case of a larger volume of oxygen in the precursor, electrical performance decreases generally. |
author2 |
School of Electrical and Electronic Engineering |
author_facet |
School of Electrical and Electronic Engineering Shiau, Li Lynn Goh, Simon Chun Kiat Wang, Xingli Zhu, MinMin Sahoo, Mamina Tan, Chuan Seng Lai, Chao-Sung Liu, Zheng Tay, Beng Kang |
format |
Article |
author |
Shiau, Li Lynn Goh, Simon Chun Kiat Wang, Xingli Zhu, MinMin Sahoo, Mamina Tan, Chuan Seng Lai, Chao-Sung Liu, Zheng Tay, Beng Kang |
author_sort |
Shiau, Li Lynn |
title |
Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
title_short |
Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
title_full |
Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
title_fullStr |
Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
title_full_unstemmed |
Effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
title_sort |
effects of precursors' purity on graphene quality : synthesis and thermoelectric effect |
publishDate |
2020 |
url |
https://hdl.handle.net/10356/142971 |
_version_ |
1681056873936060416 |