THERMOELECTRIC PROPERTIES OF MnSi1.7 FILMS WITH ADDITION OF ALUMINUM AND CARBON

2007 ◽  
Vol 21 (22) ◽  
pp. 1447-1460 ◽  
Author(s):  
Q. R. HOU ◽  
D. LIANG ◽  
X. FENG ◽  
W. ZHAO ◽  
Y. B. CHEN ◽  
...  
Keyword(s):  
Seebeck Coefficient ◽  
Activation Energies ◽  
Electron Beam Evaporation ◽  
Band Gaps ◽  
Silicon Substrates ◽  
Carbon Addition ◽  
Thermoelectric Power Factor ◽  
Higher Manganese Silicides ◽  
Reciprocal Temperature ◽  
Manganese Silicide

Polycrystalline higher manganese silicide ( MnSi 1.7, HMS) films with addition of aluminum and carbon are prepared on thermally-oxidized silicon substrates by electron beam evaporation and magnetron sputtering, respectively. An aluminum intermediate layer and a carbon cap layer are used as the doping sources. It is found that both the Seebeck coefficient and electrical resistivity are dependent on the amount of aluminum and carbon added to the films. The Seebeck coefficient changes a little in the temperature range 300 to 433 K and decreases considerably above 433 K when aluminum is added to the film. When carbon is added to the film, however, the Seebeck coefficient increases slightly. With addition of aluminum and carbon, the resistivity decreases. As a result, the thermoelectric power factor increases, especially for films with carbon addition. Several activation energies (0.022–0.20 eV) are observed from the curves of logarithm of resistivity versus reciprocal temperature. The larger activation energies of 0.35 and 0.51 eV are consistent with the energy band gaps for higher manganese silicides.

MECHANICAL AND THERMOELECTRIC PROPERTIES OF HIGHER MANGANESE SILICIDE FILMS

2006 ◽  
Vol 20 (15) ◽  
pp. 877-886 ◽  
Author(s):  
Q. R. HOU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Elastic Modulus ◽  
Magnetron Sputtering ◽  
Seebeck Coefficient ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Silicon Substrates ◽  
Energy Band Gap ◽  
Thermo Electric ◽  
Higher Manganese Silicide ◽  
Manganese Silicide

Higher manganese silicide (HMS, MnSi 1.7) films have been deposited on glass, silicon and thermally oxidized silicon substrates by the methods of magnetron sputtering and thermal evaporation. Mechanical and thermo-electric properties of the films have been measured. The hardness and elastic modulus of the films are 10.0~14.5 GPa and 156~228 GPa, respectively. The sign of the Seebeck coefficient at room temperature is positive for all samples. The resistivity at room temperature is between 0.53×10-3 and 45.6×10-3 ohm-cm. The energy band gap calculated from the resistivity data for the film deposited on thermally oxidized silicon substrate is about 0.459 eV.

INFLUENCE OF OXYGEN IMPURITY ON SEEBECK COEFFICIENT OF NANOSCALE MnSi1.7 FILMS

2009 ◽  
Vol 23 (20n21) ◽  
pp. 2421-2427 ◽  
Author(s):  
Q. R. HOU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electron Beam ◽  
Transition Temperature ◽  
Seebeck Coefficient ◽  
Thermal Annealing ◽  
Oxygen Content ◽  
Layer Structure ◽  
Electron Beam Evaporation ◽  
Silicon Substrates ◽  
Oxygen Impurity ◽  
P Type

Nano-scale MnSi 1.7 films are prepared by thermal annealing of three-layer Si / MnSi x/ Si or bi-layer Si / MnSi x (x < 1.7) structures at 923 K for 20–65 minutes. These layers are deposited on thermally oxidized silicon substrates at about 393 K by electron beam evaporation. It is found that the oxygen content in the MnSi 1.7 film can be reduced from about 10 at.% to 6 at.% by using the bi-layer structure MnSi x/ Si with the MnSi x layer on top. With the reduction of oxygen content in the MnSi 1.7 film, the transition temperature from p-type to n-type decreases from 508 K to 463 K or less.

PREPARATION OF N-TYPE HIGHER MANGANESE SILICIDE FILMS BY MAGNETRON SPUTTERING

2009 ◽  
Vol 23 (16) ◽  
pp. 3331-3348 ◽  
Author(s):  
Q. R. HOU ◽  
W. ZHAO ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Magnetron Sputtering ◽  
Seebeck Coefficient ◽  
Power Factor ◽  
Intermediate Layer ◽  
Activation Energies ◽  
Carbon Doping ◽  
Higher Manganese Silicide ◽  
Cap Layer ◽  
Manganese Silicide

N-type polycrystalline higher manganese silicide ( MnSi 1.7) films are prepared on thermally oxidized silicon substrates by magnetron sputtering. MnSi 1.85, Si , and carbon targets are used in the experiments. By co-sputtering of the MnSi 1.85 and Si targets, n-type MnSi 1.7 films are directly obtained. By increasing the Si content to the deposited films, both the Seebeck coefficient and electrical resistivity increase to high values. A Si intermediate layer between the MnSi 1.7 film and substrate plays an important role on the electrical properties of the films. Without the interlayer, the Seebeck coefficient is not stable and the electrical resistivity is higher. For preparation of MnSi 1.7 films by solid phase reaction, a sandwich structure Si / MnSi x/ Si (x < 1.7) and thermal annealing are used. A carbon cap layer is used as a doping source. With the carbon doping, the electrical resistivity of the MnSi 1.7 film decreases, while the Seebeck coefficient increases slightly. For reactive deposition, the MnSi x (x < 1.7) film is directly deposited on the heated substrate with a Si intermediate layer. By using a Si cap layer, a MnSi 1.7 film with a Seebeck coefficient of -292 μ V/K and electrical resistivity of 23 × 10-3 Ω- cm at room temperature is obtained. The power factor reaches 1636 μW/mK2 at 483 K. With such a high power factor, the n-type MnSi 1.7 material may be superior to p-type MnSi 1.7 material for the development of thermoelectric generators. Several smaller (0.036 - 0.099 eV ) and intermediate (0.10 - 0.28 eV ) activation energies are observed from the curves of logarithm of the resistivity versus reciprocal temperature. The larger activation energies (0.35 - 1.1 eV ) are consistent with the reported energy band gaps for higher manganese silicides.

Cu-induced Seebeck peak in HMS/Si film

2014 ◽  
Vol 28 (22) ◽  
pp. 1450176 ◽  
Author(s):  
Q. R. Hou ◽  
B. F. Gu ◽  
Y. B. Chen
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Bulk Material ◽  
Energy Levels ◽  
Thermoelectric Power Factor ◽  
Silicide Layer ◽  
Manganese Silicide ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
Peak Value

It is well known that aluminum ( Al ), boron ( B ) and copper ( Cu ) are acceptor impurities with shallow- and deep-energy levels in silicon ( Si ), respectively. Thus, Al and B impurities with shallow-energy levels in Si are essentially completely ionized at room temperature while Cu impurities with deep-energy levels in Si at higher temperature. In this paper, Al , B and Cu co-doped Si layer is used as a barrier layer while the higher manganese silicide layer (HMS) as a well layer. The Seebeck coefficient (S) of Al and Cu modulation doped film, HMS/ Si :( Al + Cu ), increases sharply above 583 K, reaches a peak value of 0.300 mV/K at 683 K, and then decreases with further increasing temperature. Concomitance with the great increase in Seebeck coefficient, however, the electrical resistivity (R) is still smaller than that of only Al modulation doped film, HMS/ Si : Al . The Cu -induced Seebeck peak, S max = 0.303 mV/K at 733 K, and reduction in electrical resistivity are also observed in ( B + Al + Cu ) modulation doped film, Si :( B + Al + Cu )/HMS/ Si :( B + Al + Cu ), where B is used to reduce the electrical resistivity further. As a result, the thermoelectric power factor (PF = S2/R) is greatly enhanced and can reach 3.140 × 10-3 W/m-K2 at 733 K, which is larger than that of HMS bulk material.

Influence of an interlayer on thermoelectric power factor of HMS film on quartz substrate

2014 ◽  
Vol 28 (11) ◽  
pp. 1450087
Author(s):  
Q. R. Hou ◽  
B. F. Gu ◽  
Y. B. Chen
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Quartz Substrate ◽  
Metallic Phase ◽  
The Other ◽  
Thermoelectric Power Factor ◽  
Manganese Silicide ◽  
Lower Electrical Resistivity

The influence of an AlO x oxide or Si interlayer on the thermoelectric power factor of the higher manganese silicide (HMS, MnSi y, y = 1.73–1.75) film deposited on quartz substrate is investigated. The HMS film and the interlayer are prepared on quartz substrate by magnetron sputtering of MnSi 2, Al , Si and Si : B (1 at.% B content) targets. It is found that the metallic phase MnSi is present in the semiconducting HMS film without an interlayer, resulting in a lower Seebeck coefficient, 0.160 mV/K, but not a lower electrical resistivity, 0.021 Ω ⋅cm at 683 K. The thermoelectric power factor is only 122 × 10-6 W/mK2 at 683 K. On the other hand, the metallic phase MnSi disappears and the Seebeck coefficient restores to its high value after using the AlO x oxide or Si interlayer. Besides, the electrical resistivity decreases by using the AlO x oxide or Si : B interlayer. The HMS film with an Si : B interlayer has the highest Seebeck coefficient, 0.247 mV/K, and the lowest electrical resistivity, 0.011 Ω ⋅cm, at 683 K. Thus, the thermoelectric power factor is enhanced and can reach 555 × 10-6 W/mK2 at 683 K.

Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation

1988 ◽  
Vol 46 ◽  
pp. 866-867
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
L. G. Turner ◽  
N. Lewis
Keyword(s):  
Thin Film ◽  
Thin Film Deposition ◽  
Superconducting Films ◽  
Electron Beam Evaporation ◽  
Film Deposition ◽  
Silicon Substrates ◽  
Superconducting Properties ◽  
Sequential Electron ◽  
Thin Superconducting Films

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.

Enhanced thermoelectric power factor of Re-substituted higher manganese silicides with small islands of MnSi secondary phase

2015 ◽  
Vol 3 (40) ◽  
pp. 10500-10508 ◽  
Author(s):  
Xi Chen ◽  
Jianshi Zhou ◽  
John B. Goodenough ◽  
Li Shi
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
Secondary Phase ◽  
Small Islands ◽  
Thermoelectric Power Factor ◽  
Higher Manganese Silicides ◽  
Quenching Method

A rhenium-substituted HMS sample with small islands of MnSi secondary phase has been prepared by the quenching method. Such unique microstructure leads to an enhanced thermoelectric power factor (PF) as compared to the samples prepared by other methods.

Investigation into Hardness and Young’s Modulus of Thin Films of Lead Germanium Telluride

2012 ◽  
Vol 455-456 ◽  
pp. 8-12 ◽  
Author(s):  
Bin Li ◽  
Ping Xie ◽  
Su Ying Zhang ◽  
Ding Quan Liu
Keyword(s):  
Thin Films ◽  
Young’S Modulus ◽  
Ferroelectric Phase ◽  
Young's Modulus ◽  
Strength Loss ◽  
Electron Beam Evaporation ◽  
Silicon Substrates ◽  
Strain Fields ◽  
Germanium Telluride ◽  
Nanoindentation Measurement

A mechanically robust infrared high-index coating material is essential to the infrared interference coatings. Lead germanium telluride (Pb1-xGexTe) is a pseudo-binary alloy of IV-VI narrow gap semiconductors of PbTe and GeTe. In our investigation, the hardness and Young’s modulus of thin films of Pb1-xGexTe, which were deposited on silicon substrates using electron beam evaporation, were identified by means of nanoindentation measurement. It is demonstrated that layers of Pb1-xGexTe have greater hardness and Young’s modulus compared with those of PbTe. These mechanical behaviors of layers can be linked to a ferroelectric phase transition from a cubic paraelectric phase to a rhombohedral, ferroelectric phase. Moreover, the strength loss in the layers of Pb1-xGexTe can be also explained in light of strong localized elastic-strain fields in concentrated solid solutions.

Quantum Interference Enhanced Thermoelectricity in Ferrocene Based Molecular Junctions

2019 ◽  
Vol 19 (11) ◽  
pp. 7452-7455
Author(s):  
Ashkan Vakilipour Takaloo ◽  
Hatef Sadeghi
Keyword(s):  
Seebeck Coefficient ◽  
Single Molecule ◽  
Power Factor ◽  
Quantum Interference ◽  
Room Temperature ◽  
Thermoelectric Power Factor ◽  
Molecular Scale ◽  
Single Molecule Junctions ◽  
Path Structure ◽  
Single Path

Recent experimental indications of room-temperature quantum interference in the sub-nanometer single molecules suggest that such effects could be utilized to engineer thermoelectric properties of organic single molecule junctions. In this paper, we show that the thermoelectric power factor is significantly enhanced in double path ferrocene cycles compared to the single path counterpart. Due to quantum interference in the double path structure, the Seebeck coefficient is significantly enhanced while the conductance is less affected compared to single path structure. The power factor of the ferrocene cycles are 1–2 orders of magnitude higher than the best organic material reported today. This opens new avenues for future molecular scale organometallic thermoelectricity.

scholarly journals Influence of crystallinity on the thermoelectric power factor of P3HT vapour-doped with F4TCNQ

RSC Advances ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 1593-1599 ◽  
Author(s):  
Jonna Hynynen ◽  
David Kiefer ◽  
Christian Müller
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Thermoelectric Power Factor ◽  
Order Of Magnitude

The crystallinity of P3HT strongly benefits the electrical conductivity but not Seebeck coefficient, leading to an increase in power factor by one order of magnitude.

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