Charge transport in graphene oxide
The objective of this thesis is to study charge injection across the gold/graphene-oxide (Au/GO) interface and elucidate the charge transport mechanisms in graphene oxide (GO) and lightly reduced GO (RGO). Ballistic electron emission microscopy (BEEM) studies show the Au/GO interface to be non-homog...
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| Format: | Thesis |
| Language: | English |
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2013
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| Online Access: | https://hdl.handle.net/10356/54808 |
| _version_ | 1811687410882314240 |
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| author | Rasanayagam Sivasayan Kajen |
| author2 | Pey Kin Leong |
| author_facet | Pey Kin Leong Rasanayagam Sivasayan Kajen |
| author_sort | Rasanayagam Sivasayan Kajen |
| collection | NTU |
| description | The objective of this thesis is to study charge injection across the gold/graphene-oxide (Au/GO) interface and elucidate the charge transport mechanisms in graphene oxide (GO) and lightly reduced GO (RGO). Ballistic electron emission microscopy (BEEM) studies show the Au/GO interface to be non-homogeneous at the nanoscale. In addition, the distribution of electron/hole injection barriers across the Au/GO interface was extracted via ballistic electron/hole emission spectroscopy (BHES/BEES). The heterogeneity of the interface is believed to arise due to the different functional groups on GO, which are known to create defects/traps.
Trap energy levels in GO were extracted via thermally stimulated current (TSC) measurements on graphene oxide devices, fabricated by e-beam lithography. In addition, TSC measurements carried out on RGO showed a decrease in the overall trap density compared to that of GO. However, several states close to the Fermi level are shown to emerge with reduction.
Conventional temperature dependent current-voltage (I-V) measurements on RGO measured down to 12K, showed various charge transport mechanisms such as tunneling, hopping, space charge limited current with exponentially distributed traps (SCLC-EDT), and Poole-Frenkel limited transport, depending on the applied field and temperature. The transport gap in GO/RGO is shown to be of the order of a few meV, resembling an ohmic contact.
Overall, the I-V, BEEM and TSC experiments give a correlated view of the transport in GO/RGO, supporting a multi-energy bandgap. In terms of technology, we find that several issues related to trap states have to be first resolved before GO/RGO could be used either as a dielectric or as a channel material. |
| first_indexed | 2024-10-01T05:15:53Z |
| format | Thesis |
| id | ntu-10356/54808 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T05:15:53Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | ntu-10356/548082023-07-04T16:18:13Z Charge transport in graphene oxide Rasanayagam Sivasayan Kajen Pey Kin Leong School of Electrical and Electronic Engineering DRNTU::Engineering::Electrical and electronic engineering The objective of this thesis is to study charge injection across the gold/graphene-oxide (Au/GO) interface and elucidate the charge transport mechanisms in graphene oxide (GO) and lightly reduced GO (RGO). Ballistic electron emission microscopy (BEEM) studies show the Au/GO interface to be non-homogeneous at the nanoscale. In addition, the distribution of electron/hole injection barriers across the Au/GO interface was extracted via ballistic electron/hole emission spectroscopy (BHES/BEES). The heterogeneity of the interface is believed to arise due to the different functional groups on GO, which are known to create defects/traps. Trap energy levels in GO were extracted via thermally stimulated current (TSC) measurements on graphene oxide devices, fabricated by e-beam lithography. In addition, TSC measurements carried out on RGO showed a decrease in the overall trap density compared to that of GO. However, several states close to the Fermi level are shown to emerge with reduction. Conventional temperature dependent current-voltage (I-V) measurements on RGO measured down to 12K, showed various charge transport mechanisms such as tunneling, hopping, space charge limited current with exponentially distributed traps (SCLC-EDT), and Poole-Frenkel limited transport, depending on the applied field and temperature. The transport gap in GO/RGO is shown to be of the order of a few meV, resembling an ohmic contact. Overall, the I-V, BEEM and TSC experiments give a correlated view of the transport in GO/RGO, supporting a multi-energy bandgap. In terms of technology, we find that several issues related to trap states have to be first resolved before GO/RGO could be used either as a dielectric or as a channel material. DOCTOR OF PHILOSOPHY (EEE) 2013-08-22T06:40:51Z 2013-08-22T06:40:51Z 2013 2013 Thesis Rasanayagam Sivasayan Kajen. (2013). Charge transport in graphene oxide. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/54808 10.32657/10356/54808 en 154 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Electrical and electronic engineering Rasanayagam Sivasayan Kajen Charge transport in graphene oxide |
| title | Charge transport in graphene oxide |
| title_full | Charge transport in graphene oxide |
| title_fullStr | Charge transport in graphene oxide |
| title_full_unstemmed | Charge transport in graphene oxide |
| title_short | Charge transport in graphene oxide |
| title_sort | charge transport in graphene oxide |
| topic | DRNTU::Engineering::Electrical and electronic engineering |
| url | https://hdl.handle.net/10356/54808 |
| work_keys_str_mv | AT rasanayagamsivasayankajen chargetransportingrapheneoxide |