Reference-free THz-TDS conductivity analysis of thin conducting films

We present a reference-free method to determine electrical parameters of thin conducting films by steady state transmission-mode terahertz time-domain spectroscopy (THz-TDS). We demonstrate that the frequency-dependent AC conductivity of graphene can be acquired by comparing the directly transmitted...

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Bibliographic Details
Published in:Optics express 2020-09, Vol.28 (20), p.28819-28830
Main Authors: Whelan, Patrick R., Shen, Qian, Luo, Da, Wang, Meihui, Ruoff, Rodney S., Jepsen, Peter U., Bøggild, Peter, Zhou, Binbin
Format: Article
Language:English
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Summary:We present a reference-free method to determine electrical parameters of thin conducting films by steady state transmission-mode terahertz time-domain spectroscopy (THz-TDS). We demonstrate that the frequency-dependent AC conductivity of graphene can be acquired by comparing the directly transmitted THz pulse with a transient internal reflection within the substrate which avoids the need for a standard reference scan. The DC sheet conductivity, scattering time, carrier density, mobility, and Fermi velocity of graphene are retrieved subsequently by fitting the AC conductivity with the Drude model. This reference-free method was investigated with two complementary THz setups: one commercial fibre-coupled THz spectrometer with fast scanning rate (0.2-1.5 THz) and one air-plasma based ultra-broadband THz spectrometer for greatly extended frequency range (2-10 THz). Certain propagation correction terms for more accurate retrieval of electrical parameters are discussed.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.402447