CC BY
10THz-O-1
NONLINEAR AND TERAHERTS PHOTONICS
Ultrafast pump-probe spectroscopy of 1D van der Waals heterostructures
M. Burdanova1'2. James Lloyd-Hughes3
1- Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia 2-Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny, Russia 3- University of Warwick, Department of Physics, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
Main author email address: [email protected]
A novel class of 1D nanomaterials was created by building radial heterostructures, such as wafer scale, free-standing thin films of MoS2 nanotubes grown outside BN nanotubes and carbon nanotubes[1, 2]. We examined the optoelectronic properties of atomically thin 1D van der Waals heterostructures comprising the single-walled carbon nanotubes wrapped by insulating BN layers and MoS2 outer layers (MoS2@BN@CNT). Here we will present the equilibrium properties of such materials (through optical absorption, Raman scattering, photoluminescence, FTIR and THz spectroscopy studies), and the dynamical properties of excitons and free charges (via optical pump-optical probe, and optical pump -THz probe spectroscopy). The radial heterostructure showed a unique THz photoconductivity that dynamically changed from anomalous (positive AT/T, corresponding to negative photoconductivity) to normal (positive),driven by mobile free charges in the MoS2 with a mobility comparable to high-quality 2D MoS2. In addition, optical pump-white light probe spectroscopy revealed that excitons are the primary initial photoproduct in the MoS2 nanotubes of the present vdW heterostructure. We discuss the co-existence of free charges and excitons in the heterostructure.
[1] M.G.Burdanova et al. Ultrafast optoelectronic processes in 1D radial van der Waals heterostructures: carbon, boron nitride and MoS2 nanotubes with coexisting excitons and highly mobile charges. Nano Lett., 20, 5, pp. 3560-3567, (2020)
[2] R. Xiang et al., One-dimensional van der Waals heterostructures, Science, 367, 6477, pp. 537-542 (2020)
ALT'22
