Two Valence Subbands in Single Crystals of Bismuth Telluride Doped with Lead and Its Electrical Properties

Presence of two valence subbands in bismuth telluride has been suggested before from the study of transport properties under high magnetic fields. Results of experimental investigation of electrical conductivity and Hall effect with lead‐doped Bi2Te3 are reported. It is suggested that excitation from one valence subband to another is taking place such that the total number of carriers remains unchanged but the conductivity changes exponentially due to the difference of mobilities in the two subbands. This can account for the change in the electrical conductivity in the low temperature region which cannot be satisfactorily explained so far. Hall effect in the low temperature region can also be accounted for. The mobilities of holes in the two valence subbands and electrons in the conduction band are determined.