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Journal of Physical Studies 23(4), Article 4702 [6 pages] (2019)
DOI: https://doi.org/10.30970/jps.23.4702 STRUCTURE AND THERMOELECTRIC CHARACTERISTICS OF THIN COMPOSITE FILMS BASED ON LEAD TELLURIDEYu. V. Tur1, I. S. Virt{1,2}
1Drohobych State Pedagogical University, 3, Stryiska St., UA-82100, Drohobych, Ukraine |
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The results of the investigations of structural and thermoelectric properties of thin composite films based on PbTe are given. The films of different thicknesses (10-150 nm) on glass, Al$_2$O$_3$ and silicon substrates were obtained by pulsed laser deposition of $1\times 10^{-4}$ Pa, and at different substrate temperatures (30$^\circ$\,C, 200$^\circ$\,C). The growth conditions leading to the films having different properties that could be controlled in a possibly wide range were identified. The parameters of the crystalline structure of thin films have been determined by X-ray diffractometry methods and high-energy electron diffraction methods. The surface morphology of thin PbTe composite films (initial growth stages) was investigated using a SEM scanning microscope. During the study of the morphology of the film surface, it was clearly visible that the contrasts with the main surface (matrix) of the film differ. This indicates a rather significant deviation from the stoichiometry in the process of the deposition of the films by the method of pulsed laser deposition. The temperature dependences of electrical conductivity, the Seebeck coefficient and the thermal power of thin composite films based on PbTe with inclusions have been investigated. With increasing temperature, Zeebek coefficient for the PbTe film $\langle$Sb$_2$Te$_3\rangle$ increases in absolute value from $\approx 1$\,mV/K to values $\approx 11$\,mV/K, and the electrical conductivity decreases from $\sigma \approx 0.5$\,(Ohm$\cdot$cm$^{-1}$ to $\sigma \approx 0.08$ (Ohm$\cdot$cm$^{-1}$. For other films, the temperature characteristics of the similar parameters have the opposite character. The estimation of the value of thermoelectric parameters is made taking into account the dimensional effects in the processes of charge carrier transport, and the phenomenon of increase of the Seebeck coefficient at the content of Bi$_2$Te$_3$ is indicated.
PACS number(s): 73.50.Lw, 84.60.Pb