Electronic Structure and Transport Properties of Bi2Te3 and Bi2Se3 Single Crystals

Abstract

The electrical resistivity and the Hall effect of topological insulator Bi2Te3 and Bi2Se3 single crystals were studied in the temperature range from 4.2 to 300 K and in magnetic fields up to 10 T. Theoretical calculations of the electronic structure of these compounds were carried out in density functional approach, taking into account spin–orbit coupling and crystal structure data for temperatures of 5, 50 and 300 K. A clear correlation was found between the density of electronic states at the Fermi level and the current carrier concentration. In the case of Bi2Te3, the density of states at the Fermi level and the current carrier concentration increase with increasing temperature, from 0.296 states eV−1 cell−1 (5 K) to 0.307 states eV−1 cell−1 (300 K) and from 0.9 × 1019 cm−3 (5 K) to 2.6 × 1019 cm−3 (300 K), respectively. On the contrary, in the case of Bi2Se3, the density of states decreases with increasing temperature, from 0.201 states eV−1 cell−1 (5 K) to 0.198 states eV−1 cell−1 (300 K), and, as a consequence, the charge carrier concentration also decreases from 2.94 × 1019 cm−3 (5 K) to 2.81 × 1019 cm−3 (300 K).

Using the Spark Plasma Sintering System for Fabrication of Advanced Semiconductor Materials

“…The first part of this work aims to show the possibilities of the SPS device extension and present example materials we have processed using our device. The most common methods of thermoelectric materials synthesis are direct synthesis of melted substrates [6,14,15] and mechanical alloying [14,16]. Despite the high popularity of mentioned methods, there is a need for new methods development that would allow quick materials fabrication or the synthesis of new, difficult-to-synthesize materials.…”