Thermoelectric Characterization of Bismuth Telluride Nanowires, Synthesized Via Catalytic Growth and Post‐Annealing

Hamdou, Bacel; Kimling, Johannes; Dorn, August; Pippel, Eckhard; Rostek, Raimar; Woias, Peter; Nielsch, Kornelius

doi:10.1002/adma.201202474

Cited by 75 publications

(95 citation statements)

References 40 publications

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“…For TI and thermoelectric applications, it is preferable to explore Bi 2 Se 3 nanostructures. Their extremely large surfaceto-volume ratio reveals the TI surface effect which in bulk materials can be masked by bulk transport [10,11], while morphological modulation and size control was found to have immense potential to reduce thermal conductivity through enhancing phonon boundary scattering and tuning other important for thermoelectrics parameters as the electrical conductivity and Seebeck coefficient [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Vapor–solid synthesis and enhanced thermoelectric properties of non-planar bismuth selenide nanoplates on graphene substrate

et al. 2016

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In this work, stoichiometric separate bismuth selenide (Bi 2 Se 3 ) nanoplates and continuous Bi 2 Se 3 coatings are synthesized on graphene substrate by catalystfree vapor-solid deposition method. The orientation of synthesized nanoplates relative to the substrate surface varies from heteroepitaxial (planar) to oriented under different angles (non-planar). The non-planar growth of the nanoplates was achieved for the first time by short-term carrier inert gas flow in certain temperature interval of the synthesis process. The crystallographic growth directions of non-planar nanoplates were determined from HRTEM images as well as estimated from the slope angles of non-planar nanoplates. Bi 2 Se 3 coatings consisting of combination of planar and non-planar nanoplates exhibit significantly enhanced in comparison with coating consisting of only planar coalescent Bi 2 Se 3 nanoplates thermoelectric properties. Demonstrated graphene/Bi 2 Se 3 /graphene devices may find applications in thermoelectric and photo-detection sensors.

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Section: Introductionmentioning

confidence: 99%

Vapor–solid synthesis and enhanced thermoelectric properties of non-planar bismuth selenide nanoplates on graphene substrate

et al. 2016

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“…Further details on the nanowire growth as well as on electrical and on structural characterization can be found elsewhere. 8,40 We present data for a single-crystalline, For data analysis we will concentrate on the SdH contribution 'R, which we obtain by subtracting the smooth bulk background and the WAL contribution from R (Fig. 1 d).…”

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confidence: 99%

“…Further details on the nanowire growth as well as on electrical and on structural characterization can be found elsewhere. 8,40 We present data for a single-crystalline, rectangular Bi 2 Te 3 nanowire with a cross-sectional area of (44 nm (height) x 200 nm (width)) and 1 Pm channel length (figure 1 b). The nanowire was taken from a batch which had previously yielded nanowires with pronounced WAL, SdH interferences and AB oscillations allowing for direct validation of these broadly accepted indications for the presence of TI states.…”

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confidence: 99%

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Gooth

Hamdou

Dorn

et al. 2014

Applied Physics Letters

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We validate the linear dispersion relation and resolve the Dirac cone on the surface of a single Bi 2 Te 3 nanowire via a combination of field-effect and magnetoresistance measurements by which we unambiguously prove the topological insulator nature of the nanowire surface states. Moreover we show that the experimentally determined carrier concentration, mobility and cyclotron mass of the surface states are in excellent agreement with relativistic models. Our method provides a facile way to identify topological insulators that too small for angle-resolved photo emission spectroscopy. Unambiguous experimental identification of topological insulators (TIs) requires resolving theDirac cone in the band structure of the non-trivial surface states. [1][2][3][4] Charge carriers within the surface states mimic massless Dirac fermions with extremely high mobilities, opening great opportunities for novel information processing devices. Nanowires with a high surface-tovolume ratio are of special interest because the surface state conductivity is expected to overwhelm the parasitic transport through the nanowire bulk. [5][6][7][8][9][10] While the Dirac cone has been directly detected by angle-resolved photoemission spectroscopy (ARPES) of Bi 2 Te 3 , [11][12][13] 20,37,38 While most of these works focus on reducing the relative contribution to electrical transport from the bulk by enhancing the surface contribution via field-effect, resolving the linear dispersion relation of the surface states has not been attempted so far.Our experiments were performed using a single nanowire device equipped with two electrodes for resistance measurements and a global back gate (figure 1 a). Electrical contacts to the nanowire were prepared via common laser beam lithography and subsequent sputter deposition of Ti/Pt. A highly p-doped silicon chip served as gate with a 200 nm insulating buffer layer of thermal SiO 2 on top. Standard low frequency lock-in techniques were performed in at low temperatures with a magnetic field B applied perpendicular to the current direction along the nanowire axis. Comparing two-terminal and four-terminal measurements reveal that the contact resistances to the nanowire are negligible. Linear IV-curves (SI Fig. 1) demonstrate that the electrical contacts ore ohmic. The Fermi energy of the nanowire was tuned by applying gate voltages between -10 and 30 V in 5 V steps, using a DC voltage source. Bi 2 Te 3 nanowires were grown in a single zone tube furnace on Si/SiO 2 wafers seeded by 30 nm colloidal diameter Au particles, prior to 100 h annealing in a tellurium rich atmosphere at 250 °C. Further details on the nanowire growth as well as on electrical and on structural characterization can be found elsewhere. 8,40 We present data for a single-crystalline, For data analysis we will concentrate on the SdH contribution 'R, which we obtain by subtracting the smooth bulk background and the WAL contribution from R (Fig. 1 d).We observe two dominant transport channels in the SdH spectra by tuning the gate volt...

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“…44 One approach to improving the crystallinity of such nanowires is to perform post-deposition annealing. 1,2,8,9,12,42,45 Although it is clear that such annealing can lead to increased grain sizes, what is less clear is how the microstructural evolution is connected to the initial defect arrangements or what level of intragranular disorder remains following the annealing process. We investigate these issues in this study, through an electron microscopic analysis of the microstructure of annealed Bi 2 Te 3 nanowires.…”

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confidence: 99%

“…[34][35][36] As a thermoelectric material, Bi 2 Te 3 nanowires are particularly interesting because of progress toward thermal conductivity reductions in nanowire geometries, 9,14,37,38 and the longstanding predictions of increased power factor for single-crystalline nanowires with suitably small diameters. [39][40][41] However, ECD Bi 2 Te 3 nanowires typically have significantly lower power factors compared to bulk values, 2,7,9,42,43 likely due in part to their poor as-deposited crystallinity. It should be noted that the contribution of topological surface states may also limit the thermoelectric performance of Bi 2 Te 3 nanowires to levels below bulk values.…”

mentioning

confidence: 99%

Evolution of Microstructural Disorder in Annealed Bismuth Telluride Nanowires

Erickson

Limmer

Yelton

et al. 2017

ECS J. Solid State Sci. Technol.

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Controlling the distribution of structural defects in nanostructures is important since such defects can strongly affect critical properties, including thermal and electronic transport. However, characterizing the defect arrangements in individual nanostructures is difficult because of the small length scales involved. Here, we investigate the evolution of microstructural disorder with annealing in electrochemically deposited Bi2Te3 nanowires, which are of interest for thermoelectrics. We combine Convergent Beam Electron Diffraction (CBED) and Scanning Transmission Electron Microscopy (STEM) to provide the necessary spatial and orientational resolution. We find that despite their large initial grain sizes and strong {11true2¯0} crystallographic texturing, the as-deposited nanowires still exhibit significant intragranular orientational disorder. Annealing drives both grain growth and a significant reduction in the intragranular disorder. The results are discussed in the context of the existing understanding of the initial microstructure of electrodeposited materials and the understanding of annealing microstructures in both electrochemically deposited and bulk-deformed materials. This analysis highlights the importance of assessing both the grain size and intragranular disorder in understanding the microstructural evolution of individual nanostructures.

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Thermoelectric Characterization of Bismuth Telluride Nanowires, Synthesized Via Catalytic Growth and Post‐Annealing

Cited by 75 publications

References 40 publications

Vapor–solid synthesis and enhanced thermoelectric properties of non-planar bismuth selenide nanoplates on graphene substrate

Vapor–solid synthesis and enhanced thermoelectric properties of non-planar bismuth selenide nanoplates on graphene substrate

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Evolution of Microstructural Disorder in Annealed Bismuth Telluride Nanowires

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