Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation
Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density <inline-formula><math x...
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MDPI AG
2022-08-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/12/16/2845 |
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| author | Hwa Yong Lee Mohd Musaib Haidari Eun Hee Kee Jin Sik Choi Bae Ho Park Eleanor E. B. Campbell Sung Ho Jhang |
| author_facet | Hwa Yong Lee Mohd Musaib Haidari Eun Hee Kee Jin Sik Choi Bae Ho Park Eleanor E. B. Campbell Sung Ho Jhang |
| author_sort | Hwa Yong Lee |
| collection | DOAJ |
| description | Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub></semantics></math></inline-formula>, a transition from ballistic to diffusive conduction occurs at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≃</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula> and the transport gap grows in proportion to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msqrt><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub></msqrt></semantics></math></inline-formula>. Considering the potential fluctuation related to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>e</mi><mo>−</mo><mi>h</mi></mrow></semantics></math></inline-formula> puddle, the bandgap of graphene oxide is deduced to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>E</mi><mi mathvariant="normal">g</mi></msub><mo>≃</mo><mn>30</mn><msqrt><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mspace width="3.33333pt"></mspace><mrow><mo>(</mo><msup><mn>10</mn><mn>12</mn></msup><mspace width="3.33333pt"></mspace><msup><mi>cm</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></msqrt></mrow></semantics></math></inline-formula> meV. The temperature dependence of conductivity showed metal–insulator transitions at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≃</mo><mn>0.3</mn><mo>×</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula>, consistent with Ioffe–Regel criterion. For graphene oxides at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≥</mo><mn>4.9</mn><mo>×</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula>, analysis indicated charge transport occurred via 2D variable range hopping conduction between localized <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>s</mi><msup><mi>p</mi><mn>2</mn></msup></mrow></semantics></math></inline-formula> domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content. |
| first_indexed | 2024-03-09T12:50:56Z |
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| id | doaj.art-679263900dbf46c2acd4dee6c2a07913 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-09T12:50:56Z |
| publishDate | 2022-08-01 |
| publisher | MDPI AG |
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| series | Nanomaterials |
| spelling | doaj.art-679263900dbf46c2acd4dee6c2a079132023-11-30T22:06:57ZengMDPI AGNanomaterials2079-49912022-08-011216284510.3390/nano12162845Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of OxidationHwa Yong Lee0Mohd Musaib Haidari1Eun Hee Kee2Jin Sik Choi3Bae Ho Park4Eleanor E. B. Campbell5Sung Ho Jhang6School of Physics, Konkuk University, Seoul 05029, KoreaSchool of Physics, Konkuk University, Seoul 05029, KoreaSchool of Physics, Konkuk University, Seoul 05029, KoreaSchool of Physics, Konkuk University, Seoul 05029, KoreaSchool of Physics, Konkuk University, Seoul 05029, KoreaEaStCHEM, School of Chemistry, Edinburgh University, David Brewster Road, Edinburgh EH9 3FJ, UKSchool of Physics, Konkuk University, Seoul 05029, KoreaGraphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub></semantics></math></inline-formula>, a transition from ballistic to diffusive conduction occurs at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≃</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula> and the transport gap grows in proportion to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msqrt><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub></msqrt></semantics></math></inline-formula>. Considering the potential fluctuation related to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>e</mi><mo>−</mo><mi>h</mi></mrow></semantics></math></inline-formula> puddle, the bandgap of graphene oxide is deduced to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>E</mi><mi mathvariant="normal">g</mi></msub><mo>≃</mo><mn>30</mn><msqrt><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mspace width="3.33333pt"></mspace><mrow><mo>(</mo><msup><mn>10</mn><mn>12</mn></msup><mspace width="3.33333pt"></mspace><msup><mi>cm</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></msqrt></mrow></semantics></math></inline-formula> meV. The temperature dependence of conductivity showed metal–insulator transitions at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≃</mo><mn>0.3</mn><mo>×</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula>, consistent with Ioffe–Regel criterion. For graphene oxides at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>n</mi><mi mathvariant="normal">D</mi></msub><mo>≥</mo><mn>4.9</mn><mo>×</mo><msup><mn>10</mn><mn>12</mn></msup></mrow></semantics></math></inline-formula> cm<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula>, analysis indicated charge transport occurred via 2D variable range hopping conduction between localized <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>s</mi><msup><mi>p</mi><mn>2</mn></msup></mrow></semantics></math></inline-formula> domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content.https://www.mdpi.com/2079-4991/12/16/2845graphene oxidedefect densitytransport gapband gapmetal–insulator transition2D Mott VRH |
| spellingShingle | Hwa Yong Lee Mohd Musaib Haidari Eun Hee Kee Jin Sik Choi Bae Ho Park Eleanor E. B. Campbell Sung Ho Jhang Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation Nanomaterials graphene oxide defect density transport gap band gap metal–insulator transition 2D Mott VRH |
| title | Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation |
| title_full | Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation |
| title_fullStr | Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation |
| title_full_unstemmed | Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation |
| title_short | Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation |
| title_sort | charge transport in uv oxidized graphene and its dependence on the extent of oxidation |
| topic | graphene oxide defect density transport gap band gap metal–insulator transition 2D Mott VRH |
| url | https://www.mdpi.com/2079-4991/12/16/2845 |
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