Tuning photoinduced terahertz conductivity in monolayer graphene: Optical-pump terahertz-probe spectroscopy

Kar, Srabani and Mohapatra, Dipti R and Freysz, Eric and Sood, AK (2014) Tuning photoinduced terahertz conductivity in monolayer graphene: Optical-pump terahertz-probe spectroscopy. In: PHYSICAL REVIEW B, 90 (16).

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Abstract

Optical-pump terahertz-probe differential transmission measurements of as-prepared single layer graphene (AG) (unintentionally hole dopedwith Fermi energy E-F at similar to -180 meV), nitrogen doping compensated graphene (NDG) with E-F similar to -10 meV, and thermally annealed doped graphene (TAG) are examined quantitatively to understand the opposite signs of photoinduced dynamic terahertz conductivity Delta sigma. It is negative for AG and TAG but positive for NDG. We show that the recently proposed mechanism of multiple generations of secondary hot carriers due to Coulomb interaction of photoexcited carriers with the existing carriers together with the intraband scattering can explain the change of photoinduced conductivity sign and its magnitude. We give a quantitative estimate of Delta sigma in terms of controlling parameters-the Fermi energy E-F and momentum relaxation time tau. Furthermore, the cooling of photoexcited carriers is analyzed using a supercollision model which involves a defect mediated collision of the hot carriers with the acoustic phonons, thus giving an estimate of the deformation potential.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	28 Nov 2014 04:47
Last Modified:	28 Nov 2014 04:47
URI:	http://eprints.iisc.ac.in/id/eprint/50329

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