Conduction band structure of bismuth telluride according to the optical absorption
Spectral dependences of optical absorption coefficient of w-Bi<sub>2</sub>Te<sub>3</sub> are studied in the range of 40 to 300 meV depending on the electron concentration and the sample thickness at room temperature to determine the parameters of additional subband in the conduction band of bismuth telluride and its impact on charge carrier transport. It is shown that bismuth telluride is a direct bandgap semiconductor with additional subzone in the conduction band, which is consistent with the study of quantum oscillations in w-Bi<sub>2</sub>Te<sub>3</sub> in strong magnetic fields at temperatures below 20 K.