Simultaneous Measurements of Thermal Conductivity and Seebeck Coefficients of Roughened Nanowire Arrays

2012 ◽  
Vol 1456 ◽  
Author(s):  
J. S. Sadhu ◽  
T. Hongxiang ◽  
J. Ma ◽  
J. Kim ◽  
S. Sinha
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Silicon Nanowires ◽  
Nanowire Array ◽  
Temperature Drop ◽  
Nanowire Arrays ◽  
Measured Temperature ◽  
Si Substrates ◽  
Seebeck Coefficients ◽  
Simultaneous Measurements

ABSTRACTWe report simultaneous measurements of thermal conductivity and Seebeck coefficient on array-scale silicon nanowires fabricated by metal assisted chemical etching. The measurements are conducted on the solid and the mesoporous nanowire arrays (NWAs) obtained from etching 1 ohm-cm and 0.002 ohm-cm Si substrates respectively. We demonstrate control on sidewall morphology and doping of the arrays that have an aspect ratio up to 20 and 30 % areal coverage. We employ differential frequency-domain measurements, separately on the array and the corresponding substrate to obtain the temperature drop and Seebeck voltage contribution of the nanowire array. The technique is validated by measurements on bulk silicon across the resistivity 0.002-1 ohm-cm. The Seebeck measurements reveal quenching of the phonon drag in the nanowires in comparison to the bulk in the measured temperature range of 300 K- 500 K. The Seebeck coefficient shows a ~18 % decrease in the solid NWAs and ~22 % increase in the mesoporous NWAs at room temperature. The thermal conductivity is close to Casimir limit for the solid wires while it drops to ~2.5 W/mK in the mesoporous nanowires.

Thermoelectric Properties of Silicon Nanowire Array and Spin-on Glass Composites Fabricated with CMOS-compatible Techniques

2012 ◽  
Vol 1408 ◽  
Author(s):  
Benjamin M. Curtin ◽  
John E. Bowers
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Nanowire Array ◽  
Square Lattice ◽  
Glass Composites ◽  
Si Substrates ◽  
Silicon Nanowire Array ◽  
Work Interference

ABSTRACTSilicon nanowires (NWs) are promising thermoelectric materials as they offer large reductions in thermal conductivity over bulk Si without a significant decrease in the Seebeck coefficient or electrical conductivity. In this work, interference lithography was used to pattern a square lattice photoresist template over 2 cm x 2 cm Si substrates. The resulting vertical Si NW arrays were 1 μm tall with a packing density of ~15%, and the diameter of the Si NWs were 80 - 90 nm. The Si NW arrays were then embedded in spin-on glass (SOG) to form a dense composite material with a measured thermal conductivity of 1.45 W/m-K at 300 K. Devices were fabricated for cross-plane Seebeck coefficient measurements and the Si NW/SOG composite was found to have a Seebeck coefficient of roughly -284 μV/K, which is similar to bulk Si with the same doping. We also report a combined power generation of 29.3 μW from both the Si NW array and Si substrate with a temperature difference of 56 K and 50 μm x 50 μm device area.

Thermoelectric Properties of Doped Iron Disilicide

2000 ◽  
Vol 626 ◽  
Author(s):  
Jun-ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Measured Temperature Range ◽  
Temperature Range

ABSTRACTIn order to investigate the thermoelectric properties of Re-doped β-FeSi2 (Fe1-xRexSi2), Ir-doped β-FeSi2 (Fe1-xIrxSi2), and Pt-doped β-FeSi2 (Fe1-xPtxSi2), the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of these samples have been measured in the temperature range between 300 and 1150 K. Fe1-xRexSi2 is p-type, while Fe1-xIrxSi2 and Fe1-xPt xSi2 are n-type over the measured temperature range. The solubility limits of dopant are estimated to be 0.2at% for Fe1-xRexSi2, 0.5at% for Fe1-xIrxSi2, and 1.9at% for Fe1-xPtxSi2. A maximum ZT value of 0.14 was obtained for Fe1-xPt xSi2 (x=0.03) at the temperature 847 K.

scholarly journals Annealing Effect on the Thermoelectric Properties of Bi2Te3Thin Films Prepared by Thermal Evaporation Method

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jyun-Min Lin ◽  
Ying-Chung Chen ◽  
Chi-Pi Lin
Keyword(s):  
Thin Films ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Evaporation ◽  
Thermal Evaporation Method ◽  
Si Substrates ◽  
Seebeck Coefficients

Bismuth telluride-based compounds are known to be the best thermoelectric materials within room temperature region, which exhibit potential applications in cooler or power generation. In this paper, thermal evaporation processes were adopted to fabricate the n-type Bi2Te3thin films on SiO2/Si substrates. The influence of thermal annealing on the microstructures and thermoelectric properties of Bi2Te3thin films was investigated in temperature range 100–250°C. The crystalline structures and morphologies were characterized by X-ray diffraction and field emission scanning electron microscope analyses. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature. The experimental results showed that both the Seebeck coefficient and power factor were enhanced as the annealing temperature increased. When the annealing temperature increased to 250°C for 30 min, the Seebeck coefficient and power factor of n-type Bi2Te3-based thin films were found to be about −132.02 μV/K and 6.05 μW/cm·K2, respectively.

Improving the thermoelectric performance of p-type PbSe via synergistically enhancing the Seebeck coefficient and reducing electronic thermal conductivity

2020 ◽  
Vol 8 (9) ◽  
pp. 4931-4937 ◽  
Author(s):  
Zhiwei Huang ◽  
Dongyang Wang ◽  
Caiyun Li ◽  
Jinfeng Wang ◽  
Guangtao Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Performance ◽  
Seebeck Coefficients ◽  
Electronic Thermal Conductivity ◽  
P Type

CdTe alloying dramatically enhanced the thermoelectric performance of p-type PbSe by enhancing Seebeck coefficients and reducing electronic thermal conductivity.

Silicide/Silicon Hetero-Junction Structure for Thermoelectric Applications

2015 ◽  
Vol 15 (10) ◽  
pp. 7472-7475 ◽  
Author(s):  
Dongsuk Jun ◽  
Soojung Kim ◽  
Wonchul Choi ◽  
Junsoo Kim ◽  
Taehyoung Zyung ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Electrical Energy ◽  
Multilayered Structure ◽  
Thermoelectric Device ◽  
Cmos Process ◽  
Platinum Silicide ◽  
Seebeck Coefficients ◽  
Heating And Cooling ◽  
Electrical Conductivities

We fabricated silicide/silicon hetero-junction structured thermoelectric device by CMOS process for the reduction of thermal conductivity with the scatterings of phonons at silicide/silicon interfaces. Electrical conductivities, Seebeck coefficients, power factors, and temperature differences are evaluated using the steady state analysis method. Platinum silicide/silicon multilayered structure showed an enhanced Seebeck coefficient and power factor characteristics, which was considered for p-leg element. Also, erbium silicide/silicon structure showed an enhanced Seebeck coefficient, which was considered for an n-leg element. Silicide/silicon multilayered structure is promising for thermoelectric applications by reducing thermal conductivity with an enhanced Seebeck coefficient. However, because of the high thermal conductivity of the silicon packing during thermal gradient is not a problem any temperature difference. Therefore, requires more testing and analysis in order to overcome this problem. Thermoelectric generators are devices that based on the Seebeck effect, convert temperature differences into electrical energy. Although thermoelectric phenomena have been used for heating and cooling applications quite extensively, it is only in recent years that interest has increased in energy generation.

scholarly journals A Novel Top-Down Fabrication Process for Vertically-Stacked Silicon-Nanowire Array

2020 ◽  
Vol 10 (3) ◽  
pp. 1146 ◽  
Author(s):  
Kangil Kim ◽  
Jae Keun Lee ◽  
Seung Ju Han ◽  
Sangmin Lee
Keyword(s):  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Nanowire Array ◽  
Nanowire Arrays ◽  
Fabrication Method ◽  
Top Down ◽  
Silicon Nanowire Arrays ◽  
Sensing Applications ◽  
Silicon Nanowire Array ◽  
Cross Sectional Dimension

Silicon nanowires are widely used for sensing applications due to their outstanding mechanical, electrical, and optical properties. However, one of the major challenges involves introducing silicon-nanowire arrays to a specific layout location with reproducible and controllable dimensions. Indeed, for integration with microscale structures and circuits, a monolithic wafer-level process based on a top-down silicon-nanowire array fabrication method is essential. For sensors in various electromechanical and photoelectric applications, the need for silicon nanowires (as a functional building block) is increasing, and thus monolithic integration is highly required. In this paper, a novel top-down method for fabricating vertically-stacked silicon-nanowire arrays is presented. This method enables the fabrication of lateral silicon-nanowire arrays in a vertical direction, as well as the fabrication of an increased number of silicon nanowires on a finite dimension. The proposed fabrication method uses a number of processes: photolithography, deep reactive-ion etching, and wet oxidation. In applying the proposed method, a vertically-aligned silicon-nanowire array, in which a single layer consists of three vertical layers with 20 silicon nanowires, is fabricated and analyzed. The diamond-shaped cross-sectional dimension of a single silicon nanowire is approximately 300 nm in width and 20 μm in length. The developed method is expected to result in highly-sensitive, reproducible, and low-cost silicon-nanowire sensors for various biomedical applications.

scholarly journals Enhanced Thermoelectric Characteristics of Ag2Se Nanoparticle Thin Films by Embedding Silicon Nanowires

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3072
Author(s):  
Seunggen Yang ◽  
Kyoungah Cho ◽  
Sangsig Kim
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Material ◽  
Silicon Nanowires ◽  
High Performance ◽  
Conductivity Measurement ◽  
Thermoelectric Generators ◽  
Seebeck Coefficients ◽  
Thermal Conductivities

A solution-processable Ag2Se nanoparticle thin film (NPTF) is a prospective thermoelectric material for plastic-based thermoelectric generators, but its low electrical conductivity hinders the fabrication of high performance plastic-based thermoelectric generators. In this study, we design Ag2Se NPTFs embedded with silicon nanowires (SiNWs) to improve their thermoelectric characteristics. The Seebeck coefficients are −233 and −240 µV/K, respectively, for a Ag2Se NPTF alone and a Ag2Se NPTF embedded with SiNWs. For the Ag2Se NPTF embedded with SiNWs, the electrical conductivity is improved from 0.15 to 18.5 S/m with the embedment of SiNWs. The thermal conductivities are determined by a lateral thermal conductivity measurement for nanomaterials and the thermal conductivities are 0.62 and 0.84 W/(m·K) for a Ag2Se NPTF alone and a Ag2Se NPTF embedded with SiNWs, respectively. Due to the significant increase in the electrical conductivity and the insignificant increase in its thermal conductivity, the output power of the Ag2Se NPTF embedded with SiNWs is 120 times greater than that of the Ag2Se NPTF alone. Our results demonstrate that the Ag2Se NPTF embedded with SiNWs is a prospective thermoelectric material for high performance plastic-based thermoelectric generators.

Thermopower of Bi Nanowire Array Composites.

2000 ◽  
Vol 626 ◽  
Author(s):  
T.E. Huber ◽  
M.J. Graf ◽  
C.A. Foss ◽  
P. Constant
Keyword(s):  
High Pressure ◽  
Seebeck Coefficient ◽  
Contact Resistance ◽  
Nanowire Array ◽  
High Mobility ◽  
Nanowire Arrays ◽  
Pressure Injection ◽  
Dense Arrays ◽  
Bi Nanowire ◽  
High Pressure Injection

The small effective mass and high mobility of electrons in Bi, make Bi nanowires a promising system for thermoelectric applications. Dense arrays of 20–200 nm diameter Bi nanowires were fabricated by high pressure injection of the melt. Transport properties and Seebeck coefficient were investigated for Bi nanowires with various wire diameters as a function of temperature (1 K < T < 300 K) and magnetic fields (B < 0.6 T). We discuss the problem of the contact resistance of Bi nanowire arrays.

Simultaneous measurements of Seebeck coefficient and thermal conductivity across superlattice

2002 ◽  
Vol 80 (10) ◽  
pp. 1758-1760 ◽  
Author(s):  
B. Yang ◽  
J. L. Liu ◽  
K. L. Wang ◽  
G. Chen
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Simultaneous Measurements

Thermoelectric Generating Properties of Aurivillius Compounds

2012 ◽  
Vol 77 ◽  
pp. 285-290 ◽  
Author(s):  
Hitoshi Kohri ◽  
Takayoshi Yagasaki
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Substitution Effects ◽  
Seebeck Coefficients ◽  
Refuse Derived Fuel ◽  
Thermoelectric Oxides ◽  
Electrical Resistivities ◽  
High Seebeck Coefficient ◽  
The One

Thermoelectric generator is expected as an independent source, an energy converter for co-generation with Refuse Derived Fuel (RDF) and so on. Thermoelectric materials were required high Seebeck coefficient, low electrical resistivity and low thermal conductivity. Thermoelectric oxides are suitable at the high temperature range because of chemical stability. Authors focus attention on Aurivillius compounds. The Aurivillius compounds consist of Perovskite layers and Bi-O layers. It is expected that nano-layered structure shows high Seebeck coefficient due to the quantum confinement of electron in Perovskite layers. It was reported that the Seebeck coefficient of Aurivillius phase Bi2VO5.5 was high value of -28.3 mVK-1 at 1010 K, and the electrical resistivity of the one was also high value of 0.033 Ωm at 1010 K. We investigated about element substitution effects at V site on thermoelectric properties. Bi2V1-xMxO5.5 (M=Cu, Cr, x=0, 0.05, 0.1, 0.2) were prepared by solid-state reaction and hot pressing. From the results of the electrical resistivities and the Seebeck coefficients, Cu and Cr behaved as acceptor to Bi2VO5.5. Cr was effective for reducing the thermal conductivity of Bi2VO5.5. The maximum value of dimensionless figure of merit for Bi2VO5.5 was 0.06 at 910 K.

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