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1.
《Current Applied Physics》2015,15(3):261-264
Bismuth telluride (Bi2Te3) thin films were electrodeposited at room temperature from nitric baths in the presence of a surfactant, cetyltrimethylammonium bromide (CTAB). Nearly stoichiometric Bi2Te3 thin films were obtained from electrolytes containing 7.5 mM Bi(NO3)3. The surface morphology and mechanical properties of the electrodeposited thin film were improved by the addition of CTAB to the electrolyte, while the electrical and thermoelectric properties were preserved. Post-deposition annealing in a reducing environment did not improve the electrical and thermoelectric properties, possibly because the change in the microstructure of the Bi2Te3 thin film was too small.  相似文献   

2.
范平  蔡兆坤  郑壮豪  张东平  蔡兴民  陈天宝 《物理学报》2011,60(9):98402-098402
本文采用离子束溅射Bi/Te和Sb/Te二元复合靶,直接制备n型Bi2Te3热电薄膜和p型Sb2Te3热电薄膜.在退火时间同为1 h的条件下,对所制备的Bi2Te3薄膜和Sb2Te3薄膜进行不同温度的退火处理,并对其热电性能进行表征.结果表明,在退火温度为150 ℃时,制备的n型Bi2Te3关键词: 薄膜温差电池 2Te3薄膜')" href="#">Sb2Te3薄膜 2Te3薄膜')" href="#">Bi2Te3薄膜 离子束溅射  相似文献   

3.
The temperature dependence of the Raman spectra of Bi2Te3 and Bi0.5Sb1.5Te3 thermoelectric films was investigated. The temperature coefficients of the Eg(2) peak positions were determined as –0.0137 cm–1/°C and –0.0156 cm–1/°C, respectively. The thermal expansion of the crystal caused a linear shift of the Raman peak induced by the temperature change. Based on the linear relation, a reliable and noninvasive micro‐Raman scattering method was shown to measure the thermal conductivity of the thermoelectric films. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
Thermoelectric power factor of a material significantly relies on its electrical conductivity, thermal conductivity, and Seebeck coefficient. Herein, an attempt has been made to enhance the thermoelectric power factor of In2Te3 thin films by tuning their Te composition and via Se doping. The optimum Se-doping concentration and Te composition enhanced the power factor of pristine In2Te3 films by 14 and 7.4 times, respectively. The modified chemical composition, structural characteristics, and surface morphological features of In2Te3 films are observed to be pivotal in improving their thermoelectric power factor. Overall, this study offers a facile approach to control the thermoelectric power factor of In2Te3 thin films which is significant for their futuristic applications.  相似文献   

5.
Epitaxial c-oriented Bi2Te3 films 1.2 μm in thickness are grown by the hot wall method for a low supersaturation of the vapor phase over the surface of mica substrates. The hexagonal unit cell parameters a = 4.386 Å and c = 30.452 Å of the grown films almost coincide with the corresponding parameters of stoichiometric bulk Bi2Te3 crystals. At T = 100 K, the Hall concentration of electrons in the films is on the order of 8 × 1018 cm?3, while the highest values of the thermoelectric coefficient (α ≈ 280 μV K?1) are observed at temperatures on the order of 260 K. Under impurity conduction conditions, conductivity σ of the films increases upon cooling in inverse proportion to the squared temperature. In the temperature range 100–200 K, thermoelectric power parameter α2σ of Bi2Te3 films has values of 80–90 μW cm?1 K?2.  相似文献   

6.
P-type Bi2Te3-based thermoelectric semiconductors were prepared, having a grain-refined microstructure and a preferred orientation of anisotropic crystallographic structure. Disks with a nominal composition of Bi0.5Sb1.5Te3.0 were cut from an ingot grown by the vertical Bridgman method (VBM) and deformed at 473 K under a pressure of 6.0 GPa by high-pressure torsion (HPT). The crystal orientation was characterized by X-ray diffraction. The microstructures were characterized using optical microscopy and scanning electron microscopy (SEM). It was found that the HPT disks had a fine and preferentially oriented grain compared to that of the VBM disks. Further, the power factor of the HPT disks was about twice as large as that of the VBM disks. These results indicate that HPT is effective in improving the thermoelectric properties of Bi2Te3-based thermoelectric semiconductors.  相似文献   

7.
The Fermi surface anisotropy of (Bi1?x Sbx)2Te3 single crystals (0.25 ≤ x ≤ 1) was studied by analyzing the angular dependence of the frequency of Shubnikov-de Haas oscillations and the effect of tin and silver doping on the thermoelectric power in these crystals in the temperature range 77 ≤ T ≤ 300 K. It was shown that silver doping of (Bi1?x Sbx)2Te3 mixed crystals produces acceptors, while silver in Bi2Te3 acts as a donor. Tin also exhibits acceptor properties. Both tin and silver doping of p-(Bi1?x Sbx)2Te3 mixed crystals decrease the thermoelectric power due to an increase in the hole concentration.  相似文献   

8.
N-type Bi2Te2.7Se0.3 thermoelectric thin films with thickness 800 nm have been deposited on glass substrates by flash evaporation method at 473 K. Annealing effects on the thermoelectric properties of Bi2Te2.7Se0.3 thin films were examined in the temperature range 373-573 K. The structures, morphology and chemical composition of the thin films were characterized by X-ray diffraction, field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. Thermoelectric properties of the thin films have been evaluated by measurements of the electrical resistivity and Seebeck coefficient at 300 K. The Hall coefficients were measured at room temperature by the Van der Pauw method. The carrier concentration and mobility were calculated from the Hall coefficient. The films thickness of the annealed samples was measured by ellipsometer. When annealed at 473 K, the electrical resistivity and Seebeck coefficient are 2.7 mΩ cm and −180 μV/K, respectively. The maximum of thermoelectric power factor is enhanced to 12 μW/cm K2.  相似文献   

9.
Thermoelectric properties of La or Ce-doped Bi2Te3 alloys were systematically investigated by ab initio calculations of electronic structures and Boltzmann transport equations. The Seebeck coefficient of p-type LaBi7Te12 and La2Bi6Te12 was larger than that of Bi2Te3, because La doping increased the effective mass of carriers. On the other hand, the electrical conductivity of LaBi7Te12 and La2Bi6Te12 decreased, which caused a reduction of power factor of these La-doped Bi2Te3 alloys in comparison with Bi2Te3. The influence of Ce doping on the band structure and thermoelectric properties of Bi2Te3 was similar to that of La doping. The theoretical calculation provided an insight into the transport properties of La or Ce-doped Bi2Te3-based thermoelectric materials.  相似文献   

10.
Thick Cu-doped Sb2Te3 films were deposited on flexible substrate by DC magnetron sputtering from a mosaic Cu–Sb2Te3 target. The Cu-doped Sb2Te3 films were vacuum annealed to improve their thermoelectric properties. Density functional theory was used to clarify the internal mechanism of the Cu doped into the Sb2Te3 system. The results showed that Cu substitution on a Sb site induced electronic states or impurity peaks of Sb2Te3 at a valence band maximum. The carrier concentration of the Cu-doped Sb2Te3 films increased as the Cu-doped concentration increased. However, the crystallite size and Seebeck coefficient of the Cu-doped Sb2Te3 films decreased as the Cu-doped concentration increased. Post-annealing treatment improved the microstructure and thermoelectric properties of the Cu-doped Sb2Te3 films. The maximum electrical conductivity and power factor values of 754.20 S/cm at 50 °C and 1.56 10−3 W/mK2 at 100 °C were obtained in the annealed film with a Cu-doped concentration of 3 at%.  相似文献   

11.
Ion beam sputtering process was used to deposit n-type fine-grained Bi2Te3 thin films on BK7 glass substrates at room temperature. In order to enhance the thermoelectric properties, thin films are annealed at the temperatures ranging from 100 to 400 °C. X-ray diffraction (XRD) shows that the films have preferred orientations in the c-axis direction. It is confirmed that grain growth and crystallization along the c-axis are enhanced as the annealing temperature increased. However, broad impurity peaks related to some oxygen traces increase when the annealing temperature reached 400 °C. Thermoelectric properties of Bi2Te3 thin films were investigated at room temperature. The Bi2Te3 thin films, including as-deposited, exhibit the Seebeck coefficients of −90 to −168 μV K−1 and the electrical conductivities of 3.92×102-7.20×102 S cm−1 after annealing. The Bi2Te3 film with a maximum power factor of 1.10×10−3 Wm−1 K−2 is achieved when annealed at 300 °C. As a result, both structural and transport properties have been found to be strongly affected by annealing treatment. It was considered that the annealing conditions reduce the number of potential scattering sites at grain boundaries and defects, thus improving the thermoelectric properties.  相似文献   

12.
The use of surface active liquids facilitates intense stratification of mechanically strained Bi0.5Sb1.5Te3 crystallites. A Bi0.5Sb1.5Te3 heat element with specified thickness and structure is formed by layer-by-layer deposition of “thermoelectric ink” on its free surface. A heat treatment of the formed thermoelectric element in argon at a temperature of 800 K makes it possible to minimize radically the resistance of the grain boundaries introduced into its bulk.  相似文献   

13.
The effect thermal treatment in a vacuum has on the thermoelectric properties of Sb0.9Bi1.1Te2.9Se0.1 solid solution thin films obtained via ion-beam sputtering in an argon atmosphere is considered. It is established that the specific resistance and thermopower are determined by the type and concentration of intrinsic point defects of the Sb0.9Bi1.1Te2.9Se0.1 solid solution. The power factor values are found to be comparable to those of nanostructured materials based on (Bi,Sb)2(Te,Se)3 solid solutions.  相似文献   

14.
We present a laser-based transfer method for the novel application of fabricating elements for planar thermoelectric devices. Thin films of thermoelectric chalcogenides (Bi2Te3, Bi2Se3 and Bi0.5Sb1.5Te3) were printed via laser-induced forward transfer (LIFT) onto polymer-coated substrates over large areas of up to ~15 mm2 in size. A morphological study showed that it was possible to partially preserve the polycrystalline structure of the transferred films. The films’ Seebeck coefficients after LIFT transfer were measured and resulted in ?49±1 μV/K, ?93±8 μV/K and 142±3 μV/K for Bi2Te3, Bi2Se3 and Bi0.5Sb1.5Te3, respectively, which were found to be ~23±6 % lower compared to their initial values. This demonstration shows that LIFT is suitable to transfer sensitive, functional semiconductor materials over areas up to ~15 mm2 with minimal damage onto a non-standard polymer-coated substrate.  相似文献   

15.
The electrochemical reduction processes on stainless-steel substrates from an aqueous electrolyte composed of nitric acid, Bi3+, HTeO2+, SbO+ and H2SeO3 systems were investigated using cyclic voltammetry. The thin films with a stoichiometry of Bi2Te3, Bi0.5Sb1.5Te3 and Bi2Te2.7Se0.3 have been prepared by electrochemical deposition at selected potentials. The structure, composition, and morphology of the films were studied by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM) and electron microprobe analysis (EMPA). The results showed that the films were single phase with the rhombohedral Bi2Te3 structure. The morphology and growth orientation of the films were dependent on the deposition potentials.  相似文献   

16.
Bi2Te3 is one of the most used materials for thermoelectric applications at ambient temperature. An improvement of thermoelectric performances through a suitable modification of electron and phonon transport mechanisms is predicted for low dimensional or nanostructured systems, but this requires a control of the material structure down to the nanoscale. We show that pulsed laser deposition provides control on film composition, phase and structure, necessary for a comprehension of the relationship between structure and thermoelectric properties. We have explored the role of deposition temperature, background inert gas type and pressure, laser fluence and target-to-substrate distance and we found the experimental condition ranges to obtain crystalline films containing the Bi2Te3 phase only, by comparing energy dispersive X-ray spectroscopy, Raman spectroscopy and X-ray diffraction analysis. Variations of substrate temperature and deposition gas pressure prove to be crucial also for the control of film morphology and crystallinity. Substrate type has no influence on film stoichiometry and crystallinity, but highly oriented growth can be achieved on mica due to van der Waals epitaxy.  相似文献   

17.
Thin films of Sb2Te3 and (Sb2Te3)70(Bi2Te3)30 alloy and have been deposited on precleaned glass substrate by thermal evaporation technique in a vacuum of 2?×?10?6 Torr. The structural study was carried out by X-ray diffractometer, which shows that the films are polycrystalline in nature. The grain size, microstrain and dislocation density were determined. The Seebeck coefficient was determined as the ratio of the potential difference across the films to the temperature difference. The power factor for the (Sb2Te3)70 (Bi2Te3)30 and (Sb2Te3) is found to be 19.602 and 1.066 of the film of thickness 1,500 Å, respectively. The Van der-Pauw technique was used to measure the Hall coefficient at room temperature. The carrier concentration was calculated and the results were discussed.  相似文献   

18.
以Bi2Te3/PbTe超晶格薄膜为例,分析电子在Bi2Te3量子阱中的输运过程,综合了薄膜的经典散射效应和理想量子效应,并以此混合效应为基础,在PbTe障碍层厚度一定时,模拟计算了两种混合效应中量子效应占不同比例时,Bi2Te3/PbTe超晶格热电优值的变化.在镜面反射占混合效应的0.3时,得到的热电优值与当前报道的量子阱超晶格的实验值接近. 关键词: 超晶格 粗糙界面 热电优值  相似文献   

19.
The electrochemical behaviors of BiIII, TeIV and SbIII single ions and their mixtures were investigated in nitric acid and hydrochloric acid system separately. Based on which, BixSb2−xTey thermoelectric films were prepared by potentiostatic electrodeposition from the solutions with different concentrations of BiIII, TeIV and SbIII in the two acid systems. The morphologies, compositions, structures, Seebeck coefficients and resistivities of the deposited thin films were characterized and compared by ESEM (or FESEM), EDS, XRD, Seebeck coefficient measurement system and four-probe resistivity measuring device respectively. The results show that although BixSb2−xTey thermoelectric thin film which structure is consistent with the standard pattern of Bi0.5Sb1.5Te3 can be gained in both of the two acid solutions by adjusting the deposition potential, their morphologies and thermoelectric properties have big differences in different acid solutions.  相似文献   

20.
The pursuit for a high-performance thermoelectric n-type bismuth telluride-based material is significant because n-type materials are inferior to their corresponding p-type materials in highly efficient thermoelectric modules. Herein, to improve the thermoelectric performance of an n-type Bi2Te3, we prepared Bi2Te3 nano-plates with a homogeneous sub-micron size distribution and thickness range of about a few tens of nanometers. This was achieved using a typical nano-chemical synthetic method, and the prepared materials were then spark plasma sintered to fabricate n-type nano-bulk Bi2Te3 samples. We observed a significant enhancement of the anisotropic electrical transport properties for the nano-bulk sample with a higher power factor along the in-plane direction (24.3?μW?cm?1?K?2 at 300?K) than that along the out-of-plane direction (8.1?μW?cm?1?K?2 at 300?K). However, thermal transport properties were insensitive along the measured direction for the nano-bulk sample. We used a dimensionless figure of merit ZT to calculate the thermoelectric performance. The results showed that the maximum ZT value of 0.69 was achieved along the in-plane direction at 440?K for the nano-bulk n-type Bi2Te3 sample, which was however smaller than that of the previously reported n-type samples (ZT of 1.1). We believe that a further enhancement of the ZT value in the fabricated nano-bulk sample could be accomplished by effectively removing the surface organic ligand of the Bi2Te3 nano-plate particles and optimizing the spark plasma sintering conditions, maintaining the nano-plate morphology intact.  相似文献   

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