TERAHERTZ AND OPTICAL PROPERTIES OF CARBON NANOTUBES AND THEIR HETEROSTRUCTURES
Maria G. Burdanova
Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology (State University), Russian Federation
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
Michael Staniforth
Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
Rong Xiang
Department of Mechanical Engineering, Japan.
Yuriy G Gladush
Skolkovo Institute of Science and Technology, Russian Federation.
Alexey P. Tsapenko
Aalto University, Department of Applied Physics, Finland.
Esko I. Kauppinen
Aalto University, Department of Applied Physics, Finland.
Albert G Nasibulin
Skolkovo Institute of Science and Technology, Russian Federation.
School of Chemical Engineering, Aalto University Finland.
Shigeo Maruyama
Department of Mechanical Engineering, The University of Tokyo, Japan.
James Lloyd-Hughes
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United King-dom
Abstract
Terahertz (THz) spectroscopy is an ideal non-contact and non-destructive technique that probes the electrical conductivity of nanomaterials. In this talk, we will present the current status of experimental research in the THz properties of quasi-one-dimensional (quasi-1D) materials, such as nanotubes (NTs) and NT heterostructures. In such nanomaterials, dramatic changes in the optoelectronic properties result from curvature and quantum confinement in comparison to two-dimensional (2D) nanomaterials. Many body interactions between fundamental particles in nanotubes are strongly enhanced compared with those in bulk semiconductors due to the reduced dimensionality and, thus, reduced dielectric screening. These enhanced many-body interactions lead to the formation of robust quasi-particles, such as excitons, trions, and biexcitons, which are extremely important for optoelectronic device applications.
THz and transient THz spectroscopy in a combination of transient absorption spectroscopy are ideal tools for many quasiparticles investigation, such as electrons, phonons, excitons, trions, and are highly suitable to measure their ultrafast dynamics quantitatively. In particular, we will show that doping of carbon nanotubes (CNT) allowed the suppression of the excitonic absorption transitions concurrently with an increase in the THz conductivity. Under optical excitation, samples showed photoinduced bleaching of the THz spectral conductivity and distinctly different temporal recombination dynamics. This rarely observed negative photoconductivity can be understood by trion formation. Furthermore, the ultrafast pump-probe spectroscopy across the visible and THz frequency ranges identified that in MoS2 NT in 1D van der Waals (vdW) heterostructures based on CNT, excitons coexist with a prominent population of free charges. Finally, we will show that a combination of one-dimensional CNT and two-dimensional graphene in a heterostructure possesses unique properties which are different from their individual counterparts and can be used to tune the optoelectronic properties.
This improved understanding of the transient transport dynamics of photoexcited carriers and quasiparticles is important for future nanoelectronics and THz devices built on CNTs and their heterostructures.
This work was supported by the Russian Science Foundation (project no. 21-79-10097).
Speaker
Maria Burdanova
Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology (State University), Russian Federation Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
Russia
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