Carrier dynamics of nanomaterials probed at the space- and time-limit

Studies of transition metal dichalcogenides have mostly been focused on the popular semiconducting group VI dichalcogenides with symmetry in the crystal lattice, such as MoS2, MoSe2, WS2 and WSe2. However, there exists a class of less investigated, semiconducting group VII dichalcogenides, such as R...

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Main Author: Lim, Justin Wei Xiang
Other Authors: Loh Zhi Heng
Format: Final Year Project
Language:English
Published: Nanyang Technological University 2024
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Online Access:https://hdl.handle.net/10356/175677
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spelling sg-ntu-dr.10356-1756772024-05-06T15:37:01Z Carrier dynamics of nanomaterials probed at the space- and time-limit Lim, Justin Wei Xiang Loh Zhi Heng School of Physical and Mathematical Sciences zhiheng@ntu.edu.sg Physics Ultrafast spectroscopy Transition metal dichalcogenides Time-resolved photoemission electron microscopy Ultrafast carrier dynamics Carrier-carrier scattering Studies of transition metal dichalcogenides have mostly been focused on the popular semiconducting group VI dichalcogenides with symmetry in the crystal lattice, such as MoS2, MoSe2, WS2 and WSe2. However, there exists a class of less investigated, semiconducting group VII dichalcogenides, such as ReS2, exhibiting anisotropy in its crystal lattice. They demonstrate different stacking orders in their layered form and exhibit optically polarization anisotropic behavior, adding new dimensions into controlling the optical response in the material. In this Final Year Project, we utilize femtosecond time-resolved photoemission electron microscopy with the time resolution of sub-50 fs pulses, ~160 nm spatial resolution and ~180 meV energy resolution to investigate the ultrafast free-carrier dynamics of bulk ReS2. Carrier thermalization is found to occur at early time delays of <1 ps, where two carrier-carrier scattering dimensionalities were observed. The carrier-carrier scattering dimensionality is found to be controlled by the polarization of the excitation pulse, where excitation parallel to the b-axis results in one-dimensional carrier-carrier scattering, and excitation perpendicular to the b-axis results in two-dimensional carrier-carrier scattering. The different carrier-carrier scattering dimensionalities observed demonstrates an additional degree of tunability in anisotropic TMDs which could be utilized in polarization sensitive applications of the material. Bachelor's degree 2024-05-03T01:50:32Z 2024-05-03T01:50:32Z 2024 Final Year Project (FYP) Lim, J. W. X. (2024). Carrier dynamics of nanomaterials probed at the space- and time-limit. Final Year Project (FYP), Nanyang Technological University, Singapore. https://hdl.handle.net/10356/175677 https://hdl.handle.net/10356/175677 en application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Physics
Ultrafast spectroscopy
Transition metal dichalcogenides
Time-resolved photoemission electron microscopy
Ultrafast carrier dynamics
Carrier-carrier scattering
spellingShingle Physics
Ultrafast spectroscopy
Transition metal dichalcogenides
Time-resolved photoemission electron microscopy
Ultrafast carrier dynamics
Carrier-carrier scattering
Lim, Justin Wei Xiang
Carrier dynamics of nanomaterials probed at the space- and time-limit
description Studies of transition metal dichalcogenides have mostly been focused on the popular semiconducting group VI dichalcogenides with symmetry in the crystal lattice, such as MoS2, MoSe2, WS2 and WSe2. However, there exists a class of less investigated, semiconducting group VII dichalcogenides, such as ReS2, exhibiting anisotropy in its crystal lattice. They demonstrate different stacking orders in their layered form and exhibit optically polarization anisotropic behavior, adding new dimensions into controlling the optical response in the material. In this Final Year Project, we utilize femtosecond time-resolved photoemission electron microscopy with the time resolution of sub-50 fs pulses, ~160 nm spatial resolution and ~180 meV energy resolution to investigate the ultrafast free-carrier dynamics of bulk ReS2. Carrier thermalization is found to occur at early time delays of <1 ps, where two carrier-carrier scattering dimensionalities were observed. The carrier-carrier scattering dimensionality is found to be controlled by the polarization of the excitation pulse, where excitation parallel to the b-axis results in one-dimensional carrier-carrier scattering, and excitation perpendicular to the b-axis results in two-dimensional carrier-carrier scattering. The different carrier-carrier scattering dimensionalities observed demonstrates an additional degree of tunability in anisotropic TMDs which could be utilized in polarization sensitive applications of the material.
author2 Loh Zhi Heng
author_facet Loh Zhi Heng
Lim, Justin Wei Xiang
format Final Year Project
author Lim, Justin Wei Xiang
author_sort Lim, Justin Wei Xiang
title Carrier dynamics of nanomaterials probed at the space- and time-limit
title_short Carrier dynamics of nanomaterials probed at the space- and time-limit
title_full Carrier dynamics of nanomaterials probed at the space- and time-limit
title_fullStr Carrier dynamics of nanomaterials probed at the space- and time-limit
title_full_unstemmed Carrier dynamics of nanomaterials probed at the space- and time-limit
title_sort carrier dynamics of nanomaterials probed at the space- and time-limit
publisher Nanyang Technological University
publishDate 2024
url https://hdl.handle.net/10356/175677
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