Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers
Two-dimensional (2D) van der Waals (vdW) crystals provide a platform for studies of novel phenomena and promising applications beyond traditional systems. This PhD thesis focuses on vertical 2D vdW heterostructures, including ferroelectric semiconductor junctions (FSJs), p-n junction diodes, and mag...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2023
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| Online Access: | https://eprints.nottingham.ac.uk/74386/ |
| _version_ | 1848800863798165504 |
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| author | Xie, Shihong |
| author_facet | Xie, Shihong |
| author_sort | Xie, Shihong |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Two-dimensional (2D) van der Waals (vdW) crystals provide a platform for studies of novel phenomena and promising applications beyond traditional systems. This PhD thesis focuses on vertical 2D vdW heterostructures, including ferroelectric semiconductor junctions (FSJs), p-n junction diodes, and magnetic tunnel junctions (MTJs). These have potential for non-volatile memories, ultraviolet (UV) photosensing and low-power electronics.
The ferroelectric polarization of the vdW semiconductor α-In2Se3 in graphene/α-In2Se3/graphene FSJs was switched by the bias voltage, thus producing memristive effects in the transport characteristics. These can be modified by light due to screening of the polarization by photocreated carriers. The FSJs demonstrated a high photoresponsivity (up to ~ 10^6 A/W) and a relatively fast modulation (down to ~ 0.2 ms) of the photocurrent.
The graphene/p-GaSe/n-In2Se3/graphene heterostructures were used to investigate novel mechanisms for the detection of UV light. The p-GaSe/n-In2Se3 type-II band alignment and the electric field at the vdW interfaces were found to be beneficial to suppress carrier recombination and enhance the UV-photoresponse.
Finally, the Fe3GaTe2/WSe2/Fe3GaTe2 MTJs exhibited an ideal tunnelling behaviour with a tunnel magnetoresistance (TMR) signal as large as 85 % at room temperature, breaking through the bottleneck of previous vdW MTJs that worked only at low temperatures (T < 300 K).
The findings of this work offer opportunities for further developments, including the optimization of device structures and their studies towards enhanced functionalities beyond the current state of the art. |
| first_indexed | 2025-11-14T20:58:19Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-74386 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:58:19Z |
| publishDate | 2023 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-743862023-12-12T04:40:11Z https://eprints.nottingham.ac.uk/74386/ Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers Xie, Shihong Two-dimensional (2D) van der Waals (vdW) crystals provide a platform for studies of novel phenomena and promising applications beyond traditional systems. This PhD thesis focuses on vertical 2D vdW heterostructures, including ferroelectric semiconductor junctions (FSJs), p-n junction diodes, and magnetic tunnel junctions (MTJs). These have potential for non-volatile memories, ultraviolet (UV) photosensing and low-power electronics. The ferroelectric polarization of the vdW semiconductor α-In2Se3 in graphene/α-In2Se3/graphene FSJs was switched by the bias voltage, thus producing memristive effects in the transport characteristics. These can be modified by light due to screening of the polarization by photocreated carriers. The FSJs demonstrated a high photoresponsivity (up to ~ 10^6 A/W) and a relatively fast modulation (down to ~ 0.2 ms) of the photocurrent. The graphene/p-GaSe/n-In2Se3/graphene heterostructures were used to investigate novel mechanisms for the detection of UV light. The p-GaSe/n-In2Se3 type-II band alignment and the electric field at the vdW interfaces were found to be beneficial to suppress carrier recombination and enhance the UV-photoresponse. Finally, the Fe3GaTe2/WSe2/Fe3GaTe2 MTJs exhibited an ideal tunnelling behaviour with a tunnel magnetoresistance (TMR) signal as large as 85 % at room temperature, breaking through the bottleneck of previous vdW MTJs that worked only at low temperatures (T < 300 K). The findings of this work offer opportunities for further developments, including the optimization of device structures and their studies towards enhanced functionalities beyond the current state of the art. 2023-12-12 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/74386/1/Shihong%20Xie_Thesis_20152152_Final.pdf Xie, Shihong (2023) Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers. PhD thesis, University of Nottingham. van der Waals forces heterostructures ferroelectronics |
| spellingShingle | van der Waals forces heterostructures ferroelectronics Xie, Shihong Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title | Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title_full | Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title_fullStr | Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title_full_unstemmed | Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title_short | Van der Waals Heterostructures based on Two-dimensional Ferroelectric and Ferromagnetic Layers |
| title_sort | van der waals heterostructures based on two-dimensional ferroelectric and ferromagnetic layers |
| topic | van der Waals forces heterostructures ferroelectronics |
| url | https://eprints.nottingham.ac.uk/74386/ |