Mechanical and transport properties of pseudo-binary alloys (PbTe)1−x–(SnTe)x by pressureless sintering

Structural and electrical transport properties of CdS0.9Se0.1:In thin films: effect of film thickness

Nanostructures have the potential to exhibit good thermoelectric properties by tuning and controlling their size and thickness, and the competing electrical and thermal properties can be decoupled by engineering the interface and grain boundary. In the present study, Sb2Te3 nanoplatelets with different sizes were fabricated using a practical solvothermal method. The thickness of the platelets were regulated between sizes of 10 nm and 100 nm, and the opposite edge length was varied between 1 and 10 μm by altering chemical conditions. Consequently, manipulating the grain size made it suitable to benefit the carrier transport and also block phonons for the thin platelets, resulting in a significant decrease in thermal conductivity and simultaneous increase in electrical conductivity. The results showed that the optimized figure of merit ZT, increased from 0.2 to 1.0 for thin samples, providing a comprehensive understanding of size-dependent thermoelectric performance.

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Thickness Effects for Thermoelectric Property of Antimony Telluride Nanoplatelets via Solvothermal Method.

Thin films of different thicknesses have been vacuum deposited onto clean glass plates held at room temperature using the flash evaporation technique in a vacuum of 2×10−5 Torr. The structural characterization of the bulk and the thin films was carried out using x-ray diffraction, transmission electron microscopy, and selected area electron diffraction techniques. Electrical resistance and thermoelectric power of the films were measured in the same vacuum of 2×10−5 Torr in the temperature range 300–450 K. The conduction activation energy of the films was calculated using the electrical resistivity and thermoelectric power data of the films. The thickness dependence of the activation energy observed is attributed to the polycrystalline nature of the films. Grain growth and reorientation of the grains take place during the annealing process. The thickness dependence of electrical resistivity and thermoelectric power of the films are explained by the effective mean free path model [C. R. Tellier, Thin Solid ...

Thickness and temperature dependence of electrical properties of Bi2(Te0.1Se0.9)3 thin films

Thin films with a 3Ni/1Al atomic ratio were synthesized using low-power dc planar magnetron sputtering from a nickel–aluminum alloy target. Chemical analysis revealed that a significant amount of oxygen was incorporated into the Ni–Al thin films which were prepared under a typical vacuum of ∼1×10−5 mbar. These thin films were found to exhibit a prominent temperature dependence of electrical resistance, the magnitude of which diminishes upon increasing the film thickness or the in situ deposition temperature. Cross-sectional transmission electron microscopy revealed a nanocrystalline structure of the films which changes as a function of deposition temperature. Electron diffraction indicates the existence of a single-phase face-centered cubic structure in the nanocrystallites, yet with an enormous expansion of the crystal lattice for the low temperature deposited films when compared with the intermetallic Ni3Al lattice. On raising the deposition temperature or increasing the film thickness, however, the lattice constant gradually declines toward the lattice constant of bulk Ni3Al. An attempt is made to correlate the lattice structures of the crystallites and the electrical properties of the films with the potential influence of the dissolved oxygen in the Ni–Al lattice.

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Metal-to-insulator transition in sputter deposited 3Ni/Al thin films

Electrical resistivity and thermoelectric power measurements have been carried out as a function of thickness in the temperature range 300–480 K on flash evaporated Pb0.6Sn0.4Te thin films. Electrical resistivity and thermoelectric power variation with temperature of the films suggests that they have a near‐degenerate semiconductor behavior. The effective mean‐free‐path model of classical size effect has been used to analyze the thickness dependence of resistivity and thermoelectric power. Both are found to be near‐linear functions of inverse thickness. From the analysis of the experimental data, material parameters like mean free path and Fermi energy have been evaluated. Thermoelectric figure of merit has been calculated using the measured values of thermoelectric power and electrical resistivity and by taking thermal conductivity data from the literature. Thermoelectric figure of merit is also found to be thickness and temperature dependent.

Thickness and temperature effects on thermoelectric properties of Pb0.6Sn0.4Te thin films

Thin films of Pb0.8Sn0.2Te of thicknesses varying between 360 A and 3400 A have been prepared by flash evaporation on cleaned glass substrates held at room temperature. Thermoelectric power (TEP) of these films has been evaluated by measuring the thermal emf developed by the integral method in the temperature range 300 K to 500 K. It has been found that TEP of all the films is positive and increases with temperature in the low temperature region and tends to saturate at high temperatures, beyond 400 K. This has been attributed to the pinning of the Fermi level at high temperatures. It was also found that these films did not show the expected linear dependence of TEP on the inverse film thickness.

Thermoelectric Power Studies on 1% Excess Te Doped Pb$_{\bf 0.8}$Sn$_{\bf 0.2}$Te Thin Films

Variation of conduction activation energy and resistivity with thickness in Pb0.5Sn0.5Te thin films

Anomalous temperature dependence of electrical resistivity in Pb0.8Sn0.2Te thin films

Pb0.2Sn0.8Te thin films of different thicknesses have been deposited on glass substrates by flash evaporation. Electrical resistivity and thermoelectric power measurements have been carried out in the temperature range 300-500 K as a function of film thickness. The thickness dependence of the electrical resistivity and thermoelectric power observed has been explained using the effective mean free path model of classical size effect theory. The thermoelectric power factor was calculated from the measured values of electrical resistivity and thermoelectric power. The thermoelectric power factor is found to be dependent on thickness and temperature. By taking thermal conductivity values from the literature, the thermoelectric figure of merit was also calculated and it was found that this too was dependent on the temperature and thickness.

C. Bahulayan

Papers

Thickness and temperature effects on thermoelectric properties of Pb0.6Sn0.4Te thin films

Thermoelectric Power Studies on 1% Excess Te Doped Pb$_{\bf 0.8}$Sn$_{\bf 0.2}$Te Thin Films

Variation of conduction activation energy and resistivity with thickness in Pb0.5Sn0.5Te thin films

Anomalous temperature dependence of electrical resistivity in Pb0.8Sn0.2Te thin films

Variation of electrical transport properties and thermoelectric figure of merit with thickness in 1% excess Te-doped Pb0.2Sn0.8Te thin films