The Hall and Seebeck Effects in Nonstoichiometric Bismuth Telluride

Champness, C.H.; Kipling, Arlin L.

doi:10.1139/p66-066

Cited by 46 publications

(10 citation statements)

References 12 publications

(14 reference statements)

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“…The cross section of the ribbon is set to be s = 10nm× 0.5 nm. The mobility is µ * = 2000cm 2 V −1 s −1 , taken from the bulk mobility at 80K [18]. For the phonon thermal conductivity we assumed κ L = 0.1Wm −1 K −1 estimated from the bulk values [19,20].…”

Section: Competition Between Edge and Bulk Transportmentioning

confidence: 99%

Thermoelectric transport of perfectly conducting channels in two- and three-dimensional topological insulators

Murakami

Takahashi

Tretiakov

et al. 2011

J. Phys.: Conf. Ser.

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Abstract. Topological insulators have gapless edge/surface states with novel transport properties. Among these, there are two classes of perfectly conducting channels which are free from backscattering: the edge states of two-dimensional topological insulators and the onedimensional states localized on dislocations of certain three-dimensional topological insulators. We show how these novel states affect thermoelectric properties of the systems and discuss possibilities to improve the thermoelectric figure of merit using these materials with perfectly conducting channels. IntroductionTopological insulators (TI) [1,2,3,4,5] have attracted a lot of attention in the recent years. In these materials the excitations in the bulk are gapped just like in the normal insulators, but due to specific topological properties of the band structure these insulators possess gapless modes at the edges (on the surface). These modes are topologically protected and are stable against any perturbations that do not break the time-reversal symmetry. Various novel properties of TIs have been theoretically proposed, and some of them have been experimentally observed. The advent of this class of materials has brought us renewed interest in nonmagnetic insulators which have rarely been considered as an interesting subject for studying electronic properties. The transport properties of the edge/surface excitations in topological insulators are very distinct from those of the low-energy excitations of conventional metals. In two-dimensional (2D) topological insulators, the edge states are free from elastic scattering by nonmagnetic disorder. In three-dimensional (3D) topological insulators [6,7], elastic scattering for the surface states is at least partly suppressed. It is also proposed that in certain classes of 3D topological insulators, the lattice dislocations have gapless states, which are robust against elastic backscattering by nonmagnetic disorder [8].Thus, we have two cases of topologically protected one-dimensional (1D) gapless states in topological insulators; (i) the edge states in 2D topological insulators, and (ii) the states bound to dislocations in certain 3D topological insulators. These states have similar physical properties,

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Section: Competition Between Edge and Bulk Transportmentioning

confidence: 99%

Thermoelectric transport of perfectly conducting channels in two- and three-dimensional topological insulators

Murakami

Takahashi

Tretiakov

et al. 2011

J. Phys.: Conf. Ser.

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“…The temperature dependence of the electron (hole) mobility is given by the relation µ e ≈ T −1.7 (µ h ≈ T −2.0 ) [11,30,31]. Using the mass components listed above, we estimate the electron and hole density-of-state effective mass…”

Section: Evaluation Criteria Of a Quantum Size Effect In The Bismumentioning

confidence: 99%

Thermoelectric properties of bismuth telluride nanowires in the constant relaxation-time approximation

Bejenari

Kantser

2008

Phys. Rev. B

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Electronic structure of bismuth telluride nanowires with the growth directions [110] and [015] is studied in the framework of the anisotropic effective mass method using the parabolic band approximation. The components of the electron and hole effective mass tensors for six valleys are calculated for both growth directions. For a square nanowire, in the temperature range from 77 K to 500 K, the dependence of the Seebeck coefficient S, the thermal κ and electrical conductivity σ as well as the figure of merit ZT on the nanowire thickness and on the excess hole concentration pex are investigated in the constant-relaxation-time approximation. The carrier confinement is shown to play essential role for nanowires with cross section less than 30 × 30 nm 2 . In contrast to the excess holes (impurities), the confinement decreases both the carrier concentration and the thermal conductivity but increases the maximum value of the Seebeck coefficient. The confinement effect is stronger for the direction [015] than for the direction [110] due to the carrier mass difference for these directions. In the restricted temperature range, the size quantum limit is valid when the p−type nanowire cross section is smaller than 8 × 10 nm 2 (6 × 7 nm 2 and 5 × 5 nm 2 ) at the excess hole concentration pex = 2 × 10 18 cm −3 (pex = 5 × 10 18 cm −3 and pex = 1 × 10 19 cm −3 correspondingly). The carrier confinement increases the maximum value of ZT and shifts it towards high temperatures. For the growth direction [110], the maximum value of the figure of merit for the p−type nanowire is equal to 1.4, 1.6, and 2.8, correspondingly, at temperatures 310 K, 390 K, and 480 K and the cross sections 30 × 30 nm 2 , 15 × 15 nm 2 , and 7 × 7 nm 2 (pex = 5 × 10 18 cm −3 ). At the room temperature, the figure of merit equals 1.2, 1.3, and 1.7, respectively.

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“…These studies were mainly carried out on bulk samples [1], but no much work has been reported on thin films of Bi 2 Te3 . So far very few measurements of the optical properties have been reported [2,3].…”

Section: Introductionmentioning

confidence: 99%

Optical Properties of Thermally Deposited Bismuth Telluride in the Wavelength Range of 2.5-10 µm

Morsy¹,

Fouad²,

Hashem³

et al. 1991

Acta Phys. Pol. A

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The optical constants (the refractive index n, the absorption index k and the absorption coefficient α) of Bi2 Te3 thin films were determined in the wavelenght range of 2.5 to 10 µm. The shape of the absorption edge in Bi2Te3 thin films has been determined from transmittance and reflectance measurements. The edge is of the form expected for direct transition corresponding to Eg = 0.21 eV. The optical constants were used to determine the high frequency dielectric constant εo = 58, the optical conductivity σ = σ + σ2 as well as the vołume and surface energy loss functions. All these parameters were used to get some information about the intraband and interband transitions.

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The Hall and Seebeck Effects in Nonstoichiometric Bismuth Telluride

Cited by 46 publications

References 12 publications

Thermoelectric transport of perfectly conducting channels in two- and three-dimensional topological insulators

Thermoelectric transport of perfectly conducting channels in two- and three-dimensional topological insulators

Thermoelectric properties of bismuth telluride nanowires in the constant relaxation-time approximation

Optical Properties of Thermally Deposited Bismuth Telluride in the Wavelength Range of 2.5-10 µm

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