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Hot carrier dynamics in single-layered doped graphene after the photo-excitation has been studied by ultra-broadband optical-pump/THz-probe spectroscopy (OPTP). We successfully determined the frequency-dependent carrier scattering rate Γ(ω) and Drude weight D(o) of photo-excited graphene from 1 to 8 THz. The Γ(ω) shows a strong frequency dependence and the reduction of the averaged D(o) cannot be...
The pH effect on the carrier transport of conducting polymer PEDOT:PSS has been studied by terahertz and infrared-visible spectroscopy. The neutralization of conducting polymer poly (3, 4 ethylenedioxythiophene):poly (stylene sulfonate) (PEDOT:PSS) decreased the carrier concentration and mobility, which lowered the electrical conductivity of PEDOT:PSS by five orders of magnitude with increasing pH...
Carrier dynamics in single-layered graphene has been studied by reflection-type of THz time domain spectroscopic ellipsometry (THz-TDSE) and optical-pump/THz-probe spectroscopy (OPTP). We successfully determined the frequency-dependent complex sheet conductivity of photo-excited monolayer Graphene from 0.3 to 16 THz. By analyzing with Drude model, the time dependence of Drude weight and carrier scattering...
In this study, we have investigated the temperature dependence of the optical conductivity of poly(3,4-ethylenedioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS) films measured by the combination of THz and infrared-visible spectroscopy to understand the effect of the ethylene glycol (EG) on the carrier transport. The addition of EG to the PEDOT:PSS colloidal dispersion significantly improve the...
Carrier dynamics in a single-layered graphene has been studied by reflection-type THz time-domain spectroscopic ellipsometry (THz-TDSE). THz-TDSE determines the ellipsometric parameter ρ=rp/rs by measuring the p- and s-polarized THz waveforms after the reflection form sample. We successfully obtained the frequency-dependent complex sheet conductivity of monolayer graphene from 0.3 to 20 THz. By fitting...
Carrier dynamics in a single-layered graphene has been studied by ultrabroadband terahertz time domain ellipsometric spectroscopy and time resolved optical pump THz probe technique. We successfully observed the frequency-dependent sheet conductivity of the optically-pumped graphene with and without the photo excitation. Above the optical fluence of 200 µJ/cm2, the negative conductivity indicating...
We propose and demonstrate the large-band characterization of THz powermeters with a THz time-domain spectroscopy set up including a Michelson interferometer.
We have developed an ultrabroadband terahertz time domain ellipsometry (TDSE) which covers the frequency range from 0.2 to 30 THz except for the phonon absorption band of the low temperature grown photoconductive antenna detector around 8.1 THz. The THz emitter of the system can be changed between GaP crystal from 0.1 to 7.5 THz and GaSe crystal from 9 to 30 THz. The carrier transport property of...
The effect of solvent on the carrier transport in poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was studied by the combination of THz time-domain transmission spectroscopy (0.1–3 THz) and the broadband reflectance spectroscopy (4–800 THz). While the broadband reflectance showed a plasma edge in the near infrared, the frequency dependence of the THz conductivity of PEDOT:PSS...
Novel method to evaluate the density and mobility of carriers in conductive polymers is presented. The method utilizes the broadband spectral information of THz and infrared region. Terahertz-time domain spectroscopy revealed that the strong carrier scattering induced the weakly localized carrier behavior in conductive polymer poly(3, 4-ethylenedioxythiophene):poly(styrene sulfonate acid) (PEDOT:PSS)...
We have developed the laser terahertz emission microscope that does not require Vdd-biasing and signal input: NB (non-bias)-LTEM. The NB-LTEM, also, does not require signal output via electrodes. In this paper, first of all, the position of non-electrical contact tools, in failure analysis, is show. Secondary, the basic concept and the system schematic of the NB-LTEM are described. Thirdly, how to...
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