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Novel 2D transition metal dichalcogenide synthesis methods for electronic and photonic device applications

Novel 2D transition metal dichalcogenide synthesis methods for electronic and photonic device applications
Novel 2D transition metal dichalcogenide synthesis methods for electronic and photonic device applications
Soon after the discovery of graphene, two-dimensional transition metal dichalcogenides (2D-TMDC) started to receive global attention. 2D-TMDC are Van der Waals materials like graphene except that they possess excellent semiconducting properties which makes them potential silicon alternatives for next generation electronics and optoelectronics. Nevertheless, finding a technologically applicable production method for these materials is still a key challenge. Despite there is a plethora of precursors that can be used for 2D-TMDC growth, solution-based single source precursors like ammonium tetrathiotungstate (NH4)2WS4 and ammonium tetrathiomolybdate (NH4)2MoS4 are very attractive for industrialization due to their facile processing route to produce scalable TMDC films as well as cost-effectiveness. Hence, this method was studied intensively during the last decade for MoS2 while for WS2 there was no such progress due to complications of depositing uniform single source precursor films. Therefore, the main goal of this PhD thesis is to explore novel synthesis methods for 2DWS2 and 2D-MoS2 using solution based single source precursors. Additionally, initial validation of these synthesis methods as potential industrial platforms for 2D electronics and photonics was performed by fabricating prototype devices. Leveraging from well-established solution-based synthesis of large area 2D-MoS2 films, an Indium-2D-MoS2 metal-semiconductor-metal photodiode was successfully realised using simple metallisation step. Furthermore, for the first time a large area continuous/uniform few-layer WS2 films via thermolysis of (NH4)2WS4 films was demonstrated which shows a potential application as field effect transistor device.
Finally, using solution-based single source precursors, a revolutionary direct laser synthesis of 2D-WS2 and 2D-MoS2 micro-patterns under ambient conditions has been developed.
This method offers versatility, simplicity, patternability and the possibility to create TMDC device arrays, including alloys and heterostructures with minimal lithographic or thermal overheads. The results from this work could be the cornerstone towards laser assisted direct-writing technology of 2D-TMDCs for electronics and photonics devices and circuits fabrication.
University of Southampton
Abbas, Omar
c82b3806-c66f-4310-b30f-434c5461a704
Abbas, Omar
c82b3806-c66f-4310-b30f-434c5461a704
Sazio, Pier-John
0d6200b5-9947-469a-8e97-9147da8a7158

Abbas, Omar (2020) Novel 2D transition metal dichalcogenide synthesis methods for electronic and photonic device applications. Doctoral Thesis, 218pp.

Record type: Thesis (Doctoral)

Abstract

Soon after the discovery of graphene, two-dimensional transition metal dichalcogenides (2D-TMDC) started to receive global attention. 2D-TMDC are Van der Waals materials like graphene except that they possess excellent semiconducting properties which makes them potential silicon alternatives for next generation electronics and optoelectronics. Nevertheless, finding a technologically applicable production method for these materials is still a key challenge. Despite there is a plethora of precursors that can be used for 2D-TMDC growth, solution-based single source precursors like ammonium tetrathiotungstate (NH4)2WS4 and ammonium tetrathiomolybdate (NH4)2MoS4 are very attractive for industrialization due to their facile processing route to produce scalable TMDC films as well as cost-effectiveness. Hence, this method was studied intensively during the last decade for MoS2 while for WS2 there was no such progress due to complications of depositing uniform single source precursor films. Therefore, the main goal of this PhD thesis is to explore novel synthesis methods for 2DWS2 and 2D-MoS2 using solution based single source precursors. Additionally, initial validation of these synthesis methods as potential industrial platforms for 2D electronics and photonics was performed by fabricating prototype devices. Leveraging from well-established solution-based synthesis of large area 2D-MoS2 films, an Indium-2D-MoS2 metal-semiconductor-metal photodiode was successfully realised using simple metallisation step. Furthermore, for the first time a large area continuous/uniform few-layer WS2 films via thermolysis of (NH4)2WS4 films was demonstrated which shows a potential application as field effect transistor device.
Finally, using solution-based single source precursors, a revolutionary direct laser synthesis of 2D-WS2 and 2D-MoS2 micro-patterns under ambient conditions has been developed.
This method offers versatility, simplicity, patternability and the possibility to create TMDC device arrays, including alloys and heterostructures with minimal lithographic or thermal overheads. The results from this work could be the cornerstone towards laser assisted direct-writing technology of 2D-TMDCs for electronics and photonics devices and circuits fabrication.

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Published date: March 2020

Identifiers

Local EPrints ID: 447402
URI: http://eprints.soton.ac.uk/id/eprint/447402
PURE UUID: e3c6c191-eb68-40d4-b554-9fc57b1bab7d
ORCID for Pier-John Sazio: ORCID iD orcid.org/0000-0002-6506-9266

Catalogue record

Date deposited: 10 Mar 2021 17:43
Last modified: 13 Dec 2021 06:26

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Contributors

Author: Omar Abbas
Thesis advisor: Pier-John Sazio ORCID iD

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