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Cross-Examination of Ultrafast Structural, Interfacial, and Carrier Dynamics of Supported Monolayer MoS2
journal contribution
posted on 2020-02-25, 17:52 authored by Xing He, Mazhar Chebl, Ding-Shyue YangIn this Letter, the ultrafast structural,
interfacial, and carrier
dynamics of monolayer MoS2 supported on sapphire are cross-examined
by the combination of ultrafast electron diffraction (UED) and transient
reflectivity techniques. The out-of-plane motions directly probed
by reflection UED suggest a limited anisotropy in the atomic motions
of monolayer MoS2, which is distinct from that of related
materials such as graphene and WSe2. Besides thermal diffusion,
the MoS2–sapphire interface exhibits structural
dynamics trailing those of the overlaying MoS2 and are
in stark contrast with the sapphire bulk, which is consistent with
the limited thermal boundary conductance. These structural dynamics
provide justification for the determination of carriers being trapped
by defects in ∼600 fs and releasing energy within a few picoseconds.
The rich findings attest to the strength of combining techniques with
real-time optical and direct structure probes for a detailed understanding
of dynamical processes in functional materials.