Ultrafast terahertz photoresponse of single and double-walled carbon nanotubes: Optical pump-terahertz probe spectroscopy

Kar, S and Sood, AK (2019) Ultrafast terahertz photoresponse of single and double-walled carbon nanotubes: Optical pump-terahertz probe spectroscopy. In: Carbon, 144 . pp. 731-736.

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Abstract

Photocarrier excitation in conventional semiconductors enhances the conductivity due to increased intraband absorption of terahertz (THz) radiation. We report frequency dependent photoconductivity in terahertz range after 800 nm optical pump excitation in (6,5) semiconducting single-walled carbon nanotubes (SWCNT) and double-walled carbon nanotubes (DWCNT) containing both metallic and semiconducting tubes. The real and imaginary parts of photoconductivity (Δσ(ω)) show non-Drude behavior. In SWCNT, the real part Δσ Re (ω) is positive for low frequency and negative on the high-frequency side of the terahertz spectra. In contrast, DWCNTs show negative Δσ Re (ω) on low frequency and positive on the high-frequency side. This contrasting behavior is explained using Boltzmann transport theory, where the carrier scattering rate is energy dependent. Taking the scattering rate to be dominated by short-range disorder scattering, we show that the Boltzmann transport model captures the unique experimental features of Δσ(ω), for SWCNT as well as DWCNT. Both the semiconducting and metallic nanotubes in DWCNT are shown to contribute to the observed photoconductivity.

Item Type:	Journal Article
Publication:	Carbon
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd
Keywords:	Optical pumping; Photoconductivity; Single-walled carbon nanotubes (SWCN); Statistical mechanics; Terahertz spectroscopy; Terahertz waves; Yarn, Boltzmann transport theory; Double walled carbon nanotubes; Frequency dependent; Intraband absorptions; Optical-pump terahertz-probe spectroscopy; Semiconducting tubes; Singlewalled carbon nanotube (SWCNT); Terahertz radiation, Multiwalled carbon nanotubes (MWCN)
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Nov 2022 09:56
Last Modified:	30 Nov 2022 09:56
URI:	https://eprints.iisc.ac.in/id/eprint/78353

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