ENHANCEMENT OF THERMOELECTRIC POWER FACTOR BY A SILICON SPACER IN MODULATION-DOPED Si-HMS-Si

NANO ◽  
2011 ◽  
Vol 06 (05) ◽  
pp. 481-487 ◽  
Author(s):  
Q. R. HOU ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Sandwich Structure ◽  
Silicon Layer ◽  
Modulation Doping ◽  
Thermoelectric Power Factor ◽  
Doped Silicon ◽  
Spacer Thickness ◽  
Weakly Dependent

The introduction of an un-doped silicon layer (spacer) enhances significantly the thermoelectric power factor in modulation-doped Si(Al)-MnSi1.7-Si(Al) sandwich structure. This un-doped silicon layer is inserted between the MnSi1.7 (HMS) and Al -doped silicon layers. With a proper spacer thickness, the electrical resistivity decreases sharply and is weakly dependent on temperature from 300 K to 683 K. As a result, the thermoelectric power factor can reach 0.973 × 10-3 W/m-K2 at 683 K, which is about ten times larger than that of an ordinary MnSi1.7 film without modulation doping.

Enhancement of thermoelectric power factor in CrSi2 film via Si:B addition

2015 ◽  
Vol 29 (27) ◽  
pp. 1550189
Author(s):  
Q. R. Hou ◽  
B. F. Gu ◽  
Y. B. Chen
Keyword(s):  
Electrical Resistivity ◽  
Thermoelectric Power ◽  
Raman Spectra ◽  
Power Factor ◽  
Low Temperatures ◽  
X Ray Diffraction ◽  
Thermoelectric Power Factor ◽  
X Ray ◽  
Large Enhancement ◽  
Diffraction Patterns

In this paper, we report a large enhancement in the thermoelectric power factor in CrSi2 film via Si:B (1 at.% B content) addition. The Si:B-enriched CrSi2 films are prepared by co-sputtering CrSi2 and heavily B-doped Si targets. Both X-ray diffraction patterns and Raman spectra confirm the formation of the crystalline phase CrSi2. Raman spectra also indicate the crystallization of the added Si:B. With the addition of Si:B, the electrical resistivity [Formula: see text] decreases especially at low temperatures while the Seebeck coefficient [Formula: see text] increases above 533 K. As a result, the thermoelectric power factor, [Formula: see text], is greatly enhanced and can reach [Formula: see text] at 583 K, which is much larger than that of the pure CrSi2 film.

PHONON-DRAG EFFECT OF ULTRA-THIN FeSi2 AND MnSi1.7/FeSi2 FILMS

2011 ◽  
Vol 25 (22) ◽  
pp. 1829-1838 ◽  
Author(s):  
Q. R. HOU ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Low Temperatures ◽  
Room Temperature ◽  
Phonon Drag ◽  
Drag Effect ◽  
Thermoelectric Power Factor

Phonon-drag effect usually occurs in single crystals at very low temperatures (10–200 K). Strong phonon-drag effect is observed in ultra-thin β- FeSi 2 films at around room temperature. The Seebeck coefficient of a 23 nm-thick β- FeSi 2 film can reach -1.375 mV/K at 343 K. However, the thermoelectric power factor of the film is still small, only 0.42×10-3 W/m-K2, due to its large electrical resistivity. When a 27 nm-thick MnSi 1.7 film with low electrical resistivity is grown on it, the thermoelectric power factor of the MnSi 1.7 film can reach 1.5×10-3 W/m-K2 at around room temperature. This value is larger than that of bulk MnSi 1.7 material in the same temperature range.

Effects of Oxygen-Reduction on Thermoelectric Properties of Sr0.61Ba0.39Nb2O6 Ceramics

2014 ◽  
Vol 787 ◽  
pp. 210-214 ◽  
Author(s):  
Yi Li ◽  
Jian Liu ◽  
Chun Lei Wang ◽  
Wen Bin Su ◽  
Yuan Hu Zhu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Oxygen Reduction ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Thermoelectric Power Factor

The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in various conditions, were investigated in the temperature range from 323K to 1073K. Both the electrical resistivity and the absolute Seebeck coefficient decreased with the deepening degree of oxygen-reduction. However, the decrease of the electrical resistivity had a major influence on the thermoelectric power factor. Therefore, the more heavily reduced sample can gain the higher value of thermoelectric power factor. It has been observed that the thermal conductivity increased with the deepening degree of oxygen-reduction, which indicates that the scattering of the oxygen vacancies produced by reduction does not play a dominant role in the thermal conduction. In spite of the increase of the thermal conductivity, the oxygen-reduction still promoted the thermoelectric figure of merit via the increase of the thermoelectric power factor. And the most heavily reduced Sr0.61Ba0.39Nb2O6 ceramic has the highest thermoelectric figure of merit (~0.18 at 1073 K) among all the samples.

Synthesis and thermoelectric power factor of LSCO perovskites

2005 ◽  
Vol 886 ◽  
Author(s):  
Julio E. Rodriguez
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Room Temperature ◽  
Morphological Properties ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
Thermoelectric Power Factor ◽  
X Ray

ABSTRACTMeasurements of Seebeck coefficient, S(T) and electrical resistivity, ρ(T) on polycrystalline La2−xSrxCuO4+d(LSCO) (0<x≤0.2) samples are reported. The Seebeck coefficient is positive in whole measured temperature range (77K and 300K) and it decreases with Sr content. At room temperature S(T) changes from 400 μ/K for the samples with the lowest levels of Sr to 30 μV/K for the samples with the highest Sr levels. The behavior of S(T) fits to Heikes model, which describes the behavior of Seebeck coefficient in systems where the correlated hopping is present. With the Sr content, the electrical resistivity changes its behavior from semiconducting to metallic and it took values from 2.4 to 10−3Ωcm. From S(T) and rho(T) measurements the thermoelectric power factor, PF was obtained. The maximum values for PF were about 5 μW/K2cm in the samples where x= 0.03, which are comparable to the typical values for conventional thermoelectric semiconductors. The structural and morphological properties of the samples were studied by x-ray diffraction analysis and Scanning Electron Microscopy (SEM) respectively. The behavior of transport properties opens de possibility of considering this family of perovskite-compounds as a thermoelectric material which works below room temperature.

THERMOELECTRIC EFFECT OF SILICON FILMS WITH SHALLOW- AND DEEP-LEVEL ACCEPTORS

2012 ◽  
Vol 26 (31) ◽  
pp. 1250187 ◽  
Author(s):  
Q. R. HOU ◽  
J. L. SUN ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Deep Level ◽  
Silicon Films ◽  
Thermoelectric Power Factor ◽  
Si Films ◽  
Quartz Substrates ◽  
Co Doped

Crystalline Si films with both shallow- and deep-level acceptors, Al and Cu , have been prepared on glass and quartz substrates by the methods of magnetron sputtering and Al -induced crystallization. Al and Cu are co-added in the Si films intermittently by regular pulse sputtering of Al and Cu targets during deposition of the Si films. By regulating the sputtering times of Al and Cu targets, the amounts of Al and Cu in the Si films can be controlled, and thus the Seebeck coefficient and electrical resistivity of the silicon films can be adjusted. It is found that the Al and Cu co-doped Si film has a larger Seebeck coefficient and a lower electrical resistivity at higher temperatures, as compared with that of only Al -doped Si film. As a result, the thermoelectric power factor of the Al and Cu co-doped Si film is greatly enhanced. The present experimental results will not only help us to understand the basic thermoelectric properties of semiconductors doubly doped with shallow- and deep-level impurities, but also open the possibility of enhancement of thermoelectric power factor by using this concept.

Enhancement of the thermoelectric power factor of MnSi1.7 film by modulation doping of Al and Cu

2013 ◽  
Vol 114 (3) ◽  
pp. 943-949 ◽  
Author(s):  
Q. R. Hou ◽  
B. F. Gu ◽  
Y. B. Chen ◽  
Y. J. He ◽  
J. L. Sun
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
Modulation Doping ◽  
Thermoelectric Power Factor
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