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Nonmonotonic magnetic-field dependence of transport coefficients for n -Bi-Sb semiconducting alloys

Nonmonotonic magnetic-field dependence of transport coefficients for n -Bi-Sb semiconducting alloys The transport coefficients of tellurium-doped n -Bi 1 − x Sb x semiconducting alloys (0.07 ≤ x ≤ 0.15) are studied for single-crystal samples in the temperature range 1.5 ≤ T ≤ 40 K and in magnetic fields 0 ≤ H < 20 kOe. The theory developed in this study attributes the specific features in the behavior of the transport coefficients observed in a magnetic field to a strong anisotropy of the electron spectrum and anisotropy in the electron relaxation time. It is found that the dependences of the transport coefficients on the magnetic field for H ∥ C 3 can be theoretically expressed through one anisotropy parameter δ, and those for H ∥ C 2 , by means of several anisotropy parameters, namely, γ, η, ζ, and m 3 / m 1 . It is established that the anisotropy parameter δ in the n -Bi-Sb semiconducting alloys can be estimated from measurements of the electrical resistivity ρ 22 (∞)/ρ 22 (0) ℞ δ and the Hall coefficient R 12.3 (∞)/ R 12.3 ( H → 0) ℞ δ in a magnetic field H ∥ C 3 . It is shown that the observed increase in the thermoelectric efficiency by a factor of 1.5–2.0 in the transverse magnetic fields H ∥ C 3 and H ∥ C 2 originates from the nonmonotonic dependence of the diffusion component of the thermopower Δα 22 ( H )( ∇T ∥ C 1 ) on the magnetic field. The nonmonotonic dependence of the diffusion thermopower in n -Bi-Sb semiconducting alloys is associated with the strong anisotropy of the electron spectrum, the anisotropy in the electron relaxation time, and the many-valley pattern of the spectrum. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physics of the Solid State Springer Journals

Nonmonotonic magnetic-field dependence of transport coefficients for n -Bi-Sb semiconducting alloys

Red’ko, N.; Kagan, V.
Physics of the Solid State , Volume 50 (3) – Mar 1, 2008
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References (1)

Publisher
Springer Journals
Copyright
Copyright © 2008 by Pleiades Publishing, Ltd.
Subject
Physics; Solid State Physics
ISSN
1063-7834
eISSN
1090-6460
DOI
10.1134/S1063783408030013
Publisher site
See Article on Publisher Site

Abstract

The transport coefficients of tellurium-doped n -Bi 1 − x Sb x semiconducting alloys (0.07 ≤ x ≤ 0.15) are studied for single-crystal samples in the temperature range 1.5 ≤ T ≤ 40 K and in magnetic fields 0 ≤ H < 20 kOe. The theory developed in this study attributes the specific features in the behavior of the transport coefficients observed in a magnetic field to a strong anisotropy of the electron spectrum and anisotropy in the electron relaxation time. It is found that the dependences of the transport coefficients on the magnetic field for H ∥ C 3 can be theoretically expressed through one anisotropy parameter δ, and those for H ∥ C 2 , by means of several anisotropy parameters, namely, γ, η, ζ, and m 3 / m 1 . It is established that the anisotropy parameter δ in the n -Bi-Sb semiconducting alloys can be estimated from measurements of the electrical resistivity ρ 22 (∞)/ρ 22 (0) ℞ δ and the Hall coefficient R 12.3 (∞)/ R 12.3 ( H → 0) ℞ δ in a magnetic field H ∥ C 3 . It is shown that the observed increase in the thermoelectric efficiency by a factor of 1.5–2.0 in the transverse magnetic fields H ∥ C 3 and H ∥ C 2 originates from the nonmonotonic dependence of the diffusion component of the thermopower Δα 22 ( H )( ∇T ∥ C 1 ) on the magnetic field. The nonmonotonic dependence of the diffusion thermopower in n -Bi-Sb semiconducting alloys is associated with the strong anisotropy of the electron spectrum, the anisotropy in the electron relaxation time, and the many-valley pattern of the spectrum.

Journal

Physics of the Solid State – Springer Journals

Published: Mar 1, 2008

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