Thermal conductivity of boron and of its crystal structure analoges

Golikova, O. A.; Zaĭtsev, V. K.; Орлов, В. М.; Петров, А. В.; Stil'bans, L.S.; Tkalenko, E.N.

doi:10.1002/pssa.2210210202

Cited by 46 publications

(23 citation statements)

References 8 publications

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“…A nice fitting can be obtained using constant value of l SF equal to 0.9 ± 0.1 μm and 190 ± 30 nm for electrons and holes, respectively, which are suitable values for our slightly doped n-Ge substrate and excitation close to the direct gap [9]. Assuming that the diffusive constant D is 0.010 35 m 2 s −1 for electrons and 0.0049 m 2 s −1 for holes [20], this corresponds to τ el, SF = 70 ± 20 ps for electrons and τ h, SF = 7.5 ± 2.5 ps for holes. Nevertheless, the extension of the fit with the same parameters above 1.5 eV photon energy [dashed lines in Fig.…”

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confidence: 75%

Wide-range optical spin orientation in Ge from near-infrared to visible light

et al. 2014

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Ge-based spin-photodiodes have been employed to investigate the spectral dependence of optical spin orientation in germanium, in the range 400-1550 nm. We found the expected maximum in the spin polarization of photocarriers for excitation at the direct gap in (1550 nm) and a second sizable peak due to photogeneration in the L valleys (530 nm). Data suggest distinct spin depolarization mechanisms for excitation at and L, with shorter spin relaxation times whether the X point is involved. These devices can be used as integrated photon-helicity detectors over a wide spectral range. Spin-optoelectronics is a novel branch of semiconductor spintronics, aiming at adding a new degree of freedom to optoelectronics: the photon helicity. Exploiting the interplay between the photon angular momentum and the spin of electrons, integrated emitters (spin-LEDs) and detectors (spin photodiodes) of circularly polarized light have been proposed. Although GaAs is traditionally the material of choice for spin optoelectronics, because of its direct gap allowing for efficient conversion between light and spin polarization, recently Ge has attracted a considerable attention. In fact, thanks to the inversion symmetry of the crystal and the related absence of the D Yakonov-Perel spin scattering mechanism, Ge presents a longer spin coherence time than the one of GaAs. Spin manipulation [1], spin transport [2], spin optical pumping in the infrared [3][4][5][6][7], and electrical spin injection [8] in Ge have been reported. In our previous works [9,10], we demonstrated the room temperature operation of spin-PDs based on fully epitaxial Fe/MgO/Ge(001) heterostructures, working at 0.95 eV [11,12]. However, there is still a poor understanding of electrons and holes optical spin orientation in Ge, especially at photon energies much higher than the direct gap (0.8 eV). The optical spin orientation in Ge over a wide spectral range has been theoretically investigated by Rioux and Sipe [13]. However, no experimental data for excitation far from the point of the Brillouin zone (BZ) have been reported so far. Even for GaAs, only very recently the photon energy dependence of optical spin orientation well above the absorption edge has been reported [14].In this Rapid Communication, we report on the spectral dependence of the optical spin orientation in Ge at room temperature and over a wide spectral range (400-1550 nm, corresponding to 3.1-0.8 eV), via measurements of the helicitydependent photocurrent on Ge-based spin PDs. Surprisingly enough, the maximum sensitivity to photon helicity is observed far away from the direct gap (0.8 eV), where optical pumping is supposed to produce the highest initial spin polarization. Indeed, the helicity-dependent photocurrent variation indicates a first peak around 1500 nm (0.8 eV) and then an absolute maximum of about 10% at ∼530 nm (∼2.3 eV), corresponding to optical pumping in the L valley of the Ge band structure, * christian.rinaldi@polimi.it as shown in Fig. 1(a). Fitting of our data within a simple diffusive m...

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Wide-range optical spin orientation in Ge from near-infrared to visible light

et al. 2014

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“…[6] In ordinary metals and semiconductors, and S show an opposite tendency with respect to temperature dependence. Figure 8 shows the temperature dependence of P for M V B , where P continues to increase up to room temperature, which is not surprising since and S both increase with increasing temperature, representative of an electron} phonon interaction.…”

Section: Composition and Temperature Dependence Of Power Factormentioning

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Thermoelectric Properties of Metal-Doped β-Rhombohedral Boron

Nakayama

Shimizu

Kimura

2000

Journal of Solid State Chemistry

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“…Literature data obtained for Si [39], GaAs [42–44], Ge [44–46], GaP [44,47]. For ZnTe literature data is limited [48] and could not be found for the TRTS experimental carrier density.…”

Section: Figmentioning

confidence: 99%

Direct comparison of time-resolved terahertz spectroscopy and Hall Van der Pauw methods for measurement of carrier conductivity and mobility in bulk semiconductors

2017

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Charge carrier conductivity and mobility for various semiconductor wafers and crystals were measured by ultrafast above bandgap, optically excited Time-Resolved Terahertz Spectroscopy (TRTS) and Hall Van der Pauw contact methods to directly compare these approaches and validate the use of the non-contact optical approach for future materials and in-situ device analyses. Undoped and doped silicon (Si) wafers with resistances varying over six orders of magnitude were selected as model systems since contact Hall measurements are reliably made on this material. Conductivity and mobility obtained at room temperature by terahertz transmission and TRTS methods yields the sum of electron and hole mobility which agree very well with either directly measured or literature values for corresponding atomic and photo-doping densities. Careful evaluation of the optically-generated TRTS frequency-dependent conductivity also shows it is dominated by induced free-carrier absorption rather than small probe pulse phase shifts, which is commonly ascribed to changes in the complex conductivity from sample morphology and evaluation of carrier mobility by applying Drude scattering models. Thus, in this work, the real-valued, frequency-averaged conductivity was used to extract sample mobility without application of models. Examinations of germanium (Ge), gallium arsenide (GaAs), gallium phosphide (GaP) and zinc telluride (ZnTe) samples were also made to demonstrate the general applicability of the TRTS method, even for materials that do not reliably make good contacts (e.g., GaAs, GaP, ZnTe). For these cases, values for the sum of the electron and hole mobility also compare very favorably to measured or available published data.

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Thermal conductivity of boron and of its crystal structure analoges

Cited by 46 publications

References 8 publications

Wide-range optical spin orientation in Ge from near-infrared to visible light

Wide-range optical spin orientation in Ge from near-infrared to visible light

Thermoelectric Properties of Metal-Doped β-Rhombohedral Boron

Direct comparison of time-resolved terahertz spectroscopy and Hall Van der Pauw methods for measurement of carrier conductivity and mobility in bulk semiconductors

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