Cross-Examination of Photoinitiated Carrier and Structural Dynamics of Black Phosphorus at Elevated Fluences
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| Format: | Preprint |
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2023
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| _version_ | 1866911729705811968 |
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| author | Chebl, Mazhar He, Xing Yang, Ding-Shyue |
| author_facet | Chebl, Mazhar He, Xing Yang, Ding-Shyue |
| contents | Revived attention in black phosphorus (bP) has been tremendous in the past decade. While many photoinitiated experiments have been conducted, a cross-examination of bP's photocarrier and structural dynamics is still lacking. In this report, we provide such analysis by examining time-resolved data acquired using optical transient reflectivity and reflection ultrafast electron diffraction, two complementary methods under the same experimental conditions. At elevated excitation fluences, we find that more than 90% of the photoinjected carriers are annihilated within the first picosecond (ps) and transfer their energy to phonons in a nonthermal, anisotropic fashion. Electronically, the remaining carrier density around the band edges induces a significant interaction that leads to an interlayer lattice contraction in a few ps but soon diminishes as a result of the continuing loss of carriers. Structurally, phonon-phonon scattering redistributes the energy in the lattice and results in the generation of out-of-plane coherent acoustic phonons and thermal lattice expansion. Their onset times at ~6 ps are found to be in good agreement. Later, a thermalized quasi-equilibrium state is reached following a period of about 40-50 ps. Hence, we propose a picture with five temporal regimes for bP's photodynamics. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2304_13869 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Cross-Examination of Photoinitiated Carrier and Structural Dynamics of Black Phosphorus at Elevated Fluences Chebl, Mazhar He, Xing Yang, Ding-Shyue Materials Science Chemical Physics Revived attention in black phosphorus (bP) has been tremendous in the past decade. While many photoinitiated experiments have been conducted, a cross-examination of bP's photocarrier and structural dynamics is still lacking. In this report, we provide such analysis by examining time-resolved data acquired using optical transient reflectivity and reflection ultrafast electron diffraction, two complementary methods under the same experimental conditions. At elevated excitation fluences, we find that more than 90% of the photoinjected carriers are annihilated within the first picosecond (ps) and transfer their energy to phonons in a nonthermal, anisotropic fashion. Electronically, the remaining carrier density around the band edges induces a significant interaction that leads to an interlayer lattice contraction in a few ps but soon diminishes as a result of the continuing loss of carriers. Structurally, phonon-phonon scattering redistributes the energy in the lattice and results in the generation of out-of-plane coherent acoustic phonons and thermal lattice expansion. Their onset times at ~6 ps are found to be in good agreement. Later, a thermalized quasi-equilibrium state is reached following a period of about 40-50 ps. Hence, we propose a picture with five temporal regimes for bP's photodynamics. |
| title | Cross-Examination of Photoinitiated Carrier and Structural Dynamics of Black Phosphorus at Elevated Fluences |
| topic | Materials Science Chemical Physics |
| url | https://arxiv.org/abs/2304.13869 |