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Title: Cross-examination of photoinitiated carrier and structural dynamics of black phosphorus at elevated fluences
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 article, 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.  more » « less
Award ID(s):
2154363 1653903
PAR ID:
10526920
Author(s) / Creator(s):
; ;
Publisher / Repository:
AIP Publishing
Date Published:
Journal Name:
The Journal of chemical physics
Volume:
160
Issue:
12
ISSN:
0021-9606
Page Range / eLocation ID:
124703
Subject(s) / Keyword(s):
two-dimensional materials van der Waals carrier recombination carrier–phonon coupling electronic–lattice coupling
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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