Abstract
UDC 537.9, 53.06, 53.043
DOI https://doi.org/10.5281/zenodo.1054139
Thermoelectric properties and Shubnikov de Haas (SdH) oscillations of single crystals layers of an n-type bismuth telluride topological insulator (ТI) are investigated. The monocrystalline Bi2Te3 layers are prepared by the mechanical exfoliations of layers from a monocrystalline ingot with a respective structure. From experimental data on SdH oscillations both in longitudinal (H ∥ I) and in perpendicular (H ⊥ I) magnetic fields at temperature of 2.1–4.2 K, the cyclotron effective mass, Dingle temperature and the quantum mobility of charge carriers are calculated. It is revealed that the phase shift of the Landau levels index is 0.5 both for the parallel and perpendicular magnetic fields; this finding is attributed to the Berry phase of the surface state. From temperature dependences of resistance and thermo-power, the power factor in a temperature range of 2–300 K was calculated. It is found that the maximum value of the power factor was observed in a temperature range of 100–250 K; it corresponds to the best maximum values available in literature at temperatures above 300 K for perfect single-crystals. Taking into account that heat conductivity in thin layers is essentially lower than in bulk samples, it is reasonable to expect considerable enhancement of thermoelectric efficiency over a wide temperature range, which is of great importance for the development of new highly effective thermoelectric materials based on thinner Bi2Te3 ТI layers for practical applications in thermogenerators and coolers.
Keywords: topological insulator, bismuth telluride, single-crystal layers, SdH oscillations, thermoelectricity.