Tuning the free electron concentration in Sr-doped Bi2Se3

Single crystals of Bi2Se3 doped with strontium were grown from high purity elements. The prepared single crystals were characterized using x-ray diffraction. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the actual concentrations of strontium in the studied samples. The transport properties were measured for all of the samples. The Seebeck coefficient, S, the Hall coefficient, RH, and the electrical conductivity, σ, were measured in the temperature range from 80 K to 470 K. These data indicated acceptor-like behavior of strontium in Bi2Se3. A detailed study of the doping efficiency of strontium was performed. Interestingly, the Hall mobility of the free carriers increases markedly upon doping with Sr. This effect was qualitatively explained within a model of point defects in the crystal lattice of Bi2−xSrxSe3, which implied a decrease in the concentration of scattering centers.