Effect of Initial Bulk Material Composition on Thermoelectric Properties of Bi2Te3 Thin Films

Budnik, A. V.; Рогачева, Е. И.; Пинегин, В. И.; Sipatov, A. Yu.; Fedorov, Andrei G.

doi:10.1007/s11664-012-2439-1

Cited by 14 publications

(7 citation statements)

References 11 publications

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“…The results of measurements of S and RH showed that in the entire temperature range studied in this work, the samples with Te concentrations less than ~ 60.8 at. % Te exhibit p-type conductivity, and samples with higher Te concentration exhibit n-type conductivity, which is consistent with the available literature data [1][2][3][7][8][9][10][11][12][13][14][15][16]. Concentrations of both electrons (n) and holes (p) were estimated using RH values at n(p) ~ 10 19 cm -3 , indicating a strong degeneracy of electron and hole gases.…”

Section: Resultssupporting

confidence: 88%

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Effect of Deviation from Stoichiometry on Thermoelectric Properties of Bi2Te3 Polycrystals and Thin Films in the Temperature Range 77-300 K

Рогачева¹,

Novák²,

Дорошенко³

et al. 2019

J. Nano- Electron. Phys.

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Bi2Te3 semiconductor compound and Bi2Te3-based solid solutions are presently among the best lowtemperature thermoelectric materials. One of the methods of controlling the conductivity type and properties of Bi2Te3 is changing the stoichiometry of this compound. Earlier, we have obtained the room-temperature dependences of mechanical and thermoelectric properties of Bi2Te3 polycrystals on the degree of deviation from stoichiometry. The goal of this work is to investigate the behavior of such dependences at other temperatures. Bismuth telluride polycrystals with compositions in the range of 59.6-67.5 at. % Te were obtained, and for all the crystals the Seebeck coefficient, the Hall coefficient, electrical conductivity and charge carrier mobility were measured in the temperature range 77-300 K. On the basis of the temperature dependences, the isotherms of kinetic coefficients were plotted. It was found that similar to the room-temperature isotherms, the isotherms at lower temperatures were non-monotonic: they exhibited inversion of the conductivity sign between 60.5 and 61.0 at. % Te and extrema near 60.0 and 63.0 at. % Te. The experimental data are interpreted taking into account changes in the band and defect structures of Bi2Te3 under varying stoichiometry. The obtained results make it possible to control thermoelectric properties of Bi2Te3 polycrystals in the temperature range 77-300 K by changing the degree of deviation from stoichiometry.

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Section: Resultssupporting

confidence: 88%

“…% Te, S, RH and H practically do not change with the composition. It was shown that the composition of crystals with different stoichiometry and type of conductivity is fairly well reproduced in films obtained by thermal evaporation in vacuum of these crystals [16][17][18].…”

Section: Introductionmentioning

confidence: 97%

Effect of Deviation from Stoichiometry on Thermoelectric Properties of Bi2Te3 Polycrystals and Thin Films in the Temperature Range 77-300 K

Рогачева¹,

Novák²,

Дорошенко³

et al. 2019

J. Nano- Electron. Phys.

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“…45,46 The film thickness and surface roughness were controlled using a calibrated quartz resonator. The error of determining d did not exceed 65%.…”

mentioning

confidence: 99%

“…This corresponded to results we had obtained earlier on Bi 2 Te 3 films. 45,46 The in-plane electrical conductivity r and the Hall coefficient R H were measured using a conventional dc method and a magnetic field of 0.8 T on bulk parallelepiped-shaped samples and double Hall-cross shaped thin films. Six Ohmic contacts were prepared by soldering indium to the film surface.…”

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confidence: 99%

Thickness dependent quantum oscillations of transport properties in topological insulator Bi2Te3 thin films

Рогачева

Budnik

Sipatov

et al. 2015

Applied Physics Letters

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The dependences of the electrical conductivity, the Hall coefficient, and the Seebeck coefficient on the layer thickness d (d ¼ 18À600 nm) of p-type topological insulator Bi 2 Te 3 thin films grown by thermal evaporation in vacuum on glass substrates were obtained at room temperature. In the thickness range of d ¼ 18-100 nm, sustained oscillations with a substantial amplitude were revealed. The observed oscillations are well approximated by a harmonic function with a period Dd ¼ (9.5 6 0.5) nm. At d > 100 nm, the transport coefficients practically do not change as d is increased. The oscillations of the kinetic properties are attributed to the quantum size effects due to the hole confinement in the Bi 2 Te 3 quantum wells. The results of the theoretical calculations of Dd within the framework of a model of an infinitely deep potential well are in good agreement with the experimental results. It is suggested that the substantial amplitude of the oscillations and their sustained character as a function of d are connected with the topologically protected gapless surface states of Bi 2 Te 3 and are inherent to topological insulators. V C 2015 AIP Publishing LLC.

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“…Equation 1 reveals that decreasing heat conductivity is an excellent strategy. However, other strategies have been developed to boost thermoelectric efficiency, including expanding the Seebeck coefficient by electronic band topologies and band changes [8] and decreasing thermal conductivity via nano-induced-configuration as thin films and/or ball-milled [9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Reclaim of Wrecked Bi-Te Based Materials In Peltier Modules In Thermopower Properties By Mechanical Milling

Mehmet

Yüzüak

2023

Cumhuriyet Science Journal

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We thoroughly evaluated the effects of various treatments on the structural and electrical properties of the two as-cast materials, “Sb-doping Bi-Te (p-type)” and “Se-doping Bi-Te (n-type)” which are frequently present in abandoned Peltier modules. To investigate the thermoelectric properties of Bi2Te3-based materials, waste alloys characterized by electrical conductivity using the hot-end method. Alloys were purified by performing arc melting on a water-cooled copper crucible in a vacuum of at least 10-3 mbar, with five times melting sessions to assure homogeneity. A single and long milling period of 144 hours is applied. After the compressing operation, the resulting discs with nanostructures were annealed for an hour at 600 K under vacuum conditions. The discs' structural properties were characterized using X-ray diffraction (XRD) and their surfaces and stoichiometries were determined using scanning electron microscopy with an energy dispersive feature. The Seebeck coefficient of the nanoparticle formed n-type Bi-Te based sample is -35.3 µV.K-1 and p-type Bi-Te based sample is 100 µV.K-1 (15% of mean error margin). It was found that a notable improvement was attained in comparison to the initial state with the addition of nanoparticles.We thoroughly evaluated the effects of various treatments on the structural and electrical properties of the two as-cast materials, “Sb-doping Bi-Te (p-type)” and “Se-doping Bi-Te (n-type)”, which are frequently present in abandoned Peltier modules. To investigate the thermoelectric properties of Bi2Te3-based materials, waste alloys were produced and separated by electrical conductivity using the hot-end method. The alloys were purified by performing arc melting on a water-cooled copper crucible in a vacuum of at least 10-3 mbar, with 5 times melting sessions to assure homogeneity. A ball-milled procedure was used to reduce the obtained mass-scale materials to nano sizes. Single and long milling period of 144 hours is applied. After the compressing operation, the resulting discs with nano-structures were annealed for an hour at 600 K in a vacuum. X-ray diffraction was used to characterize the discs' structures, while scanning electron microscopy and energy dispersive X-ray spectroscopy were used to examine the discs' surfaces and determine their morphologies. Based on thermal imaging camera scans and Si-diode, we know that the Seebeck coefficient of the nanoparticle formed n-type Bi-Te based sample is -35.37 V.K-1, while that of the nanoparticle formed p-type Bi-Te based sample is 100.05 V.K-1 (15% of mean error margin). It was found that a notable improvement was attained in comparison to the initial state with the addition of nanoparticles.

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Effect of Initial Bulk Material Composition on Thermoelectric Properties of Bi2Te3 Thin Films

Cited by 14 publications

References 11 publications

Effect of Deviation from Stoichiometry on Thermoelectric Properties of Bi2Te3 Polycrystals and Thin Films in the Temperature Range 77-300 K

Effect of Deviation from Stoichiometry on Thermoelectric Properties of Bi2Te3 Polycrystals and Thin Films in the Temperature Range 77-300 K

Thickness dependent quantum oscillations of transport properties in topological insulator Bi2Te3 thin films

Reclaim of Wrecked Bi-Te Based Materials In Peltier Modules In Thermopower Properties By Mechanical Milling

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