Lifetime of Charge Carriers in Multiwalled Nanotubes

Zamkov, Mikhail; Woody, N.; Shan, Bing; Chang, Zenghu; Richard, Patrick

doi:10.1103/physrevlett.94.056803

Cited by 18 publications

(15 citation statements)

References 22 publications

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“…. We note that large-diameter MWCNTs are characterized as Fermi-liquid systems, 23 which justifies the use of the Fermi-Dirac distribution function, f͑T͒. Experimentally, T e ͑t͒ can be determined by probing the width of the charge energy distribution near E F .…”

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confidence: 92%

Probing the intrinsic conductivity of multiwalled carbon nanotubes

Zamkov

Alnaser

Shan

et al. 2006

Applied Physics Letters

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The authors report the two-photon electron emission study of quantum transport parameters in multiwalled carbon nanotubes. The present experimental approach is based on measurements of the electron-phonon scattering dynamics and does not employ any electrical contacts, which dramatically reduces the uncertainty in the determination of an electron mean-free path l. It is found that near the Fermi level (<0.1eV) the ballistic travel of electrons averages around 4μm, which is comparable to the nanotube length, whereas in high-current regime (⩾0.3eV) l decreases to less than 1μm.

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mentioning

confidence: 92%

Probing the intrinsic conductivity of multiwalled carbon nanotubes

Zamkov

Alnaser

Shan

et al. 2006

Applied Physics Letters

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“…To analyze the lifetimes ( 's) or the decay rates (1/ 's) of the CN's, three kinds of femtosecond timeresolved experimental techniques are available, which are the photoelectron spectroscopy, 15 16 the transmission spectroscopy, [17][18][19][20][21][22][23] and the fluorescence spectroscopy. 24-27 * Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Inelastic Coulomb Scatterings of Doped Armchair Carbon Nanotubes

Chiu¹,

Lee²,

Lin³

2010

J. Nanosci. Nanotech.

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For doped armchair carbon nanotubes, the free electrons in the conduction bands would cause the intraband single-particle and collective excitations. Both kinds of excitations would be split into two modes because of two different Fermi-momentum states (kF'S). The excited carriers might be deexcited through such Coulomb excitations. Regarding the case where the transferred momentum L = 0, the two single-particle and the lower-frequency collective excitation modes could be the efficient deexcitation channels. In the lowest bands, the decay rates of the electron states exhibit weak Fermi energy (E(F)) dependence, but the decay rates of the hole states become greater with the increase of E(F) except for the right-side k(F). Concerning the states in the higher bands, the L not equal 0 excitations also take part in the deexcitation processes. Both the electron and hole states have the same decay rates except for the case where the carriers decay to the lowest states. The decay rates contrast sharply with those of undoped carbon nanotubes and two-dimensional intercalated graphenes. It is domenated by the Fermi energy, the geometric structure and the dimensionalities. The femtosecond time-resolved photoelectron, transmission and fluorescence spectroscopies could be used to verify the predicted results.

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“…Hence, the electron distribution can be described by a F-D statistics with a definable temperature, T e . In multi-wall carbon nanotubes and graphite, the internal thermalization occurs at ~0.2 ps, 19,20 but for metallic systems it is significantly faster (~10 fs 21 ). The (Fig.2b) shows the data for the electron distribution at 570 fs after the excitation, well described by the F-D distribution with an elevated temperature of 2000±100 K. The cutoff for the spectrum is at ~1.5 eV (determined by the pump photon energy), while only a limited number of carriers are excited up to this energy.…”

Section: In This Letter We Present the Temperature Dependence Of Thementioning

confidence: 99%

“…Further details of the experimental setup can be found elsewhere. 19 Our sample was 100 µm thick freestanding ''bucky'' paper with an outer diameter of the nanotubes of 4±1 nm provided by the Nanolab.The probe-photon energy exceeds the work function of the sample by ~0.25 eV, thus directly promoting electrons from below the Fermi level, E F , to the vacuum level. The initial state energy (E − E F ) of the photoemitted electrons with respect to E F is obtained from their E kin , since (E − E F ) = E kin + eΦ − hv probe , with eΦ the work function of the sample and hv probe = 4.71 eV the energy of the probe beam.…”

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confidence: 99%

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Electron temperature dependence of the electron-phonon coupling strength in double-wall carbon nanotubes

Chatzakis¹

2013

Applied Physics Letters

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We applied Time-Resolved Two-Photon Photoemission spectroscopy to probe the electronphonon (e-ph) coupling strength in double-wall carbon nanotubes. The e-ph energy transfer rate G(T e ,T l ) from the electronic system to the lattice depends linearly on the electron (T e ) and lattice (T l ) temperatures for T e >Θ Debye . Moreover, we numerically solved the Two-Temperature Model.We found: (i) a T e decay with a 3.5 ps time constant and no significant change in T l ; (ii) an e-ph coupling factor of 2×10 16 W/m 3 ; (iii) a mass-enhancement parameter, λ, of (5.4±0.9)×10 -4 ; and (iv) a decay time of the electron energy density to the lattice of 1.34±0.85 ps. In carbon nanotubes 1 and graphene 2 , the electron-phonon (e-ph) interactions modify the dynamics of the charge carriers near the Fermi level by changing their mass and the relaxation rate. A dramatic manifestation of these interactions is found in superconductivity, in ballistic transport 3-9 phenomena in Raman spectra, 10 and in phonon dispersion. 11 A significant rise in the electron temperature, T e , with respect to the lattice temperature, T l , can be achieved by irradiating the material with ultra-short laser pulses. The e and ph systems equilibrate by exchanging energy (via scattering processes) with a rate defined by the coupling strength. The observed energy bottleneck suggests that only a limited set of the total phonon modes 12, 13 participate in the relaxation of the charge carrier energy. The e-ph coupling strength is highly important, and although it has been extensively investigated in single-wall carbon nanotubes (SWNTs) 4,9,14,15 and graphene, 16 very little is known for double-wall nanotubes (DWNTs).In this letter, we present the temperature dependence of the energy transfer rate G(T e ,T l ) from electrons to the lattice in DWNTs. Using time-resolved two-photon photoemission (TR-TPP) spectroscopy 17 , we record the non-thermal and the thermal evolution of the electron distributions and their subsequent equilibration with phonons. We analyze the dynamics of the excited electrons in the vicinity of the Fermi level and determine the e-ph interactions. We also solve numerically the Two-Temperature Model (TTM), which describes the hot electron and phonon energy evolution after the excitation. The e-ph coupling arises from the coupling in the inner tube, the coupling in the outer tube, and the coupling from electrons scattered from the inner to the outer tubes, though no significant increase in the total e-ph coupling in DWNTs compared to separate SWNTs was found 18 .In our experiment, IR ultra-short laser pulses were utilized to generate a non-equilibrium population of charge carriers in the conduction band by absorbing energy from the pulses. Further details of the experimental setup can be found elsewhere. 19 Our sample was 100 µm thick freestanding ''bucky'' paper with an outer diameter of the nanotubes of 4±1 nm provided by the Nanolab.The probe-photon energy exceeds the work function of the sample by ~0.25 eV, thus directly promoting elec...

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Lifetime of Charge Carriers in Multiwalled Nanotubes

Cited by 18 publications

References 22 publications

Probing the intrinsic conductivity of multiwalled carbon nanotubes

Probing the intrinsic conductivity of multiwalled carbon nanotubes

Inelastic Coulomb Scatterings of Doped Armchair Carbon Nanotubes

Electron temperature dependence of the electron-phonon coupling strength in double-wall carbon nanotubes

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