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Picosecond energy transfer in a transition metal dichalcogenide-graphene heterostructure revealed by transient Raman spectroscopy.

ABSTRACT: Intense light–matter interactions and unique structural and electrical properties make van der Waals heterostructures composed by graphene (Gr) and monolayer transition metal dichalcogenides (TMD) promising building blocks for tunneling transistors and flexible electronics, as well as optoelectronic devices, including photodetectors, photovoltaics, and quantum light emitting devices (QLEDs), bright and narrow-line emitters using minimal amounts of active absorber material. The performance of such devices is critically ruled by interlayer interactions which are still poorly understood in many respects. Specifically, two classes of coupling mechanisms have been proposed, charge transfer (CT) and energy transfer (ET), but their relative efficiency and the underlying physics are open questions. Here, building on a time-resolved Raman scattering experiment, we determine the electronic temperature profile of Gr in response to TMD photoexcitation, tracking the picosecond dynamics of the G and 2D Raman bands. Compelling evidence for a dominant role of the ET process accomplished within a characteristic time of ∼4 ps is provided. Our results suggest the existence of an intermediate process between the observed picosecond ET and the generation of a net charge underlying the slower electric signals detected in optoelectronic applications.

SUBMITTER: Ferrante C

PROVIDER: S-EPMC9169783 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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Picosecond energy transfer in a transition metal dichalcogenide-graphene heterostructure revealed by transient Raman spectroscopy.

Ferrante Carino C Di Battista Giorgio G López Luis E Parra LEP Batignani Giovanni G Lorchat Etienne E Virga Alessandra A Berciaud Stéphane S Scopigno Tullio T

Proceedings of the National Academy of Sciences of the United States of America 20220405 15

Intense light–matter interactions and unique structural and electrical properties make van der Waals heterostructures composed by graphene (Gr) and monolayer transition metal dichalcogenides (TMD) promising building blocks for tunneling transistors and flexible electronics, as well as optoelectronic devices, including photodetectors, photovoltaics, and quantum light emitting devices (QLEDs), bright and narrow-line emitters using minimal amounts of active absorber material. The performance of suc ...[more]

PMID: 35380900

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Project description:High-quality VO[Formula: see text] films were fabricated on top of c-Al[Formula: see text]O[Formula: see text] substrates using Reactive Bias Target Ion Beam Deposition (RBTIBD) and the studies of graphene/VO[Formula: see text] heterostructure were conducted. Graphene layers were placed on top of [Formula: see text] 50 and [Formula: see text] 100 nm VO[Formula: see text]. The graphene layers were introduced using mechanical exfoliate and CVD graphene wet-transfer method to prevent the worsening crystallinity of VO[Formula: see text], to avoid the strain effect from lattice mismatch and to study how VO[Formula: see text] can affect the graphene layer. Slight increases in graphene/VO[Formula: see text] T[Formula: see text] compared to pure VO[Formula: see text] by [Formula: see text] 1.9 [Formula: see text]C and [Formula: see text] 3.8 [Formula: see text]C for CVD graphene on 100 and 50 nm VO[Formula: see text], respectively, were observed in temperature-dependent resistivity measurements. As the strain effect from lattice mismatch was minimized in our samples, the increase in T[Formula: see text] may originate from a large difference in the thermal conductivity between graphene and VO[Formula: see text]. Temperature-dependent Raman spectroscopy measurements were also performed on all samples, and the G-peak splitting into two peaks, G[Formula: see text] and G[Formula: see text], were observed on graphene/VO[Formula: see text] (100 nm) samples. The G-peak splitting is a reversible process and may originates from in-plane asymmetric tensile strain applied under the graphene layer due to the VO[Formula: see text] phase transition mechanism. The 2D-peak measurements also show large blue-shifts around 13 cm[Formula: see text] at room temperature and slightly red-shifts trend as temperature increases for 100 nm VO[Formula: see text] samples. Other electronic interactions between graphene and VO[Formula: see text] are expected as evidenced by 2D-peak characteristic observed in Raman measurements. These findings may provide a better understanding of graphene/VO[Formula: see text] and introduce some new applications that utilize the controllable structural properties of graphene via the VO[Formula: see text] phase transition.

Dataset Information

Picosecond energy transfer in a transition metal dichalcogenide-graphene heterostructure revealed by transient Raman spectroscopy.

Publications

Picosecond energy transfer in a transition metal dichalcogenide-graphene heterostructure revealed by transient Raman spectroscopy.

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