Ultrafast Spectral Photoresponse of Bilayer Graphene: Optical Pump-Terahertz Probe Spectroscopy

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Title
Ultrafast Spectral Photoresponse of Bilayer Graphene: Optical Pump-Terahertz Probe Spectroscopy
Author(s)
Srabani Kar; Van Luan Nguyen; Dipti R. Mohapatra; Young Hee Lee; A. K. Sood
Publication Date
2018-02
Journal
ACS NANO, v.12, no.2, pp.1785 - 1792
Publisher
AMER CHEMICAL SOC
Abstract
Photoinduced terahertz conductivity Δσ(ω) of Bernal stacked bilayer graphene (BLG) with different dopings is measured by time-resolved optical pump terahertz probe spectroscopy. The real part of photoconductivity Δσ( ω) (ΔσRe(ω)) is positive throughout the spectral range 0.5-2.5 THz in low-doped BLG. This is in sharp contrast to Δσ( ω) for high-doped bilayer graphene where ΔσRe(ω) is negative at low frequency and positive on the high frequency side. We use Boltzmann transport theory to understand quantitatively the frequency dependence of Δσ( ω), demanding the energy dependence of different scattering rates such as short-range impurity scattering, Coulomb scattering, carrier-acoustic phonon scattering, and substrate surface optical phonon scattering. We find that the short-range disorder scattering dominates over other processes. The calculated photoconductivity captures very well the experimental conductivity spectra as a function of lattice temperature varying from 300 to 4 K, without any empirical fitting procedures adopted so far in the literature. This helps us to understand the intraband conductivity of photoexcited hot carriers in 2D materials. © 2018 American Chemical Society
URI
https://pr.ibs.re.kr/handle/8788114/4443
ISSN
1936-0851
Appears in Collections:
Center for Integrated Nanostructure Physics(나노구조물리 연구단) > Journal Papers (저널논문)
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