Narrow Results

In this paper, the Seebeck effect of mutilwalled carbon nanotube films has been studied. The carbon nanotubes were synthesized by hot filament chemical vapor deposition using Ni-Fe as a catalyst. It was found that the thermoelectromotive force (thermo emf) changed approximately linearly with the temperature at the hot end at room temperature, and the Seebeck coefficient of carbon nanotube films was about 10~50 μv/k. The experimental results were discussed in detail.

A narrow-gap semiconductor FeGa₃ has attracted much interest for its unusual physical properties, in particular, for its colossal thermopower at low temperatures for which the origin has not been elucidated yet. In this study, the temperature-dependence data of the conductivity, the Hall coefficient, and the Seebeck coefficient on FeGa₃ samples reported by Wagner-Reetz et al. [Phys. Rev. B 90, 195206 (2014)] have been analyzed with including the effects of impurity Hubbard bands. As a result, it is shown that, contrary to the claim by Wagner-Reetz et al., the large negative peak of the Seebeck coefficient is not due to the phonon-drag effect but due to hopping conduction in the impurity Hubbard bands. The significant effect of nonpolar-optical-phonon scattering on free-electron conduction is also pointed out.

Nano-scale Al-doped silicon films are prepared by magnetron sputtering. The amount of Al doped in the films is controlled by regulating the Al sputtering power and duration. With appropriate amount of Al, the Seebeck coefficient of the Si films at room temperature is larger than 168 μV/K, which increases with temperature in agreement with the conventional theory for three-dimensional semiconductors. By reducing the Al sputtering time, however, step-like Seebeck coefficient versus temperature is observed. This anomalous behavior is explained by the step-like density of states for two-dimensional semiconductors.

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-FeSi₂ films at around room temperature. The Seebeck coefficient of a 23 nm-thick β-FeSi₂ 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.

Thermoelectric source has proven its efficaciousness as a clean and affordable alternative energy source. Thermoelectric generators are the ones which can produce electricity from heat. The concept of thermoelectricity, its production and its related concepts are reviewed in this paper. Peltier tile, a device used as a TEG, is used in various ways to produce electricity which are thoroughly reviewed in this paper. Thermoelectricity produces from these tiles proves to be a very good source of alternate energy. Despite technological revolutions, there are many places devoid of electricity due to various reasons. Thermoelectricity generation would prove to be a very clean and affordable alternative energy source in these areas. This paper reviews TEG how it generates a clean, affordable and easily accessible energy: electricity, without the need of transmission lines.