Electron-phonon scattering in β-Ga2O3 studied by ultrafast transmission spectroscopy

Resistivity temperature â€“ dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron â€“ dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

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When band convergence is not beneficial for thermoelectrics

Nature Communications ◽

10.1038/s41467-021-23839-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Junsoo Park ◽

Maxwell Dylla ◽

Yi Xia ◽

Max Wood ◽

G. Jeffrey Snyder ◽

...

Keyword(s):

Charge Carrier ◽

First Principles ◽

Design Principle ◽

Phonon Scattering ◽

Charge Carrier Concentration ◽

Deformation Potential ◽

Interband Scattering ◽

Improved Performance ◽

Full Heusler ◽

Electron Phonon Scattering

AbstractBand convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg2Sb2-CaZn2Sb2 Zintl system and full Heusler Sr2SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

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2D weak anti-localization in thin films of the topological semimetal Pd$$_{3}$$Bi$$_{2}$$S$$_{2}$$

Scientific Reports ◽

10.1038/s41598-021-91930-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shama ◽

R. K. Gopal ◽

Goutam Sheet ◽

Yogesh Singh

Keyword(s):

Thin Films ◽

Phonon Scattering ◽

Surface States ◽

Relaxation Mechanism ◽

Transport Studies ◽

Bulk Carriers ◽

Topological Semimetal ◽

Topological Surface ◽

First Time ◽

Electron Phonon Scattering

AbstractPd$$_{3}$$ 3 Bi$$_{2}$$ 2 S$$_{2}$$ 2 (PBS) is a recently proposed topological semimetal candidate. However, evidence for topological surface states have not yet been revealed in transport measurements due to the large mobility of bulk carriers. We report the growth and magneto-transport studies of PBS thin films where the mobility of the bulk carriers is reduced by two orders of magnitude, revealing for the first time, contributions from the 2-dimensional (2D) topological surface states in the observation of the 2D weak anti-localization (WAL) effect in magnetic field and angle dependent conductivity measurements. The magnetotransport data is analysed within the 2D Hikami-Larkin-Nagaoka (HLN) theory. The analysis suggests that multiple conduction channels contribute to the transport. It is also found that the temperature dependence of the dephasing length can’t be explained only by electron-electron scattering and that electron-phonon scattering also contributes to the phase relaxation mechanism in PBS films.

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