Tuning carrier type and density in Bi2Se3 by Ca-doping

The carrier type and density in Bi2Se3 single crystals are systematically tuned by introducing a calcium (Ca) dopant. A carrier density of similar to 1x10(17) cm(-3) which corresponds to similar to 25 meV in the Fermi energy is obtained in both n- and p-type materials. Electrical transport properties show that the insulating behavior is achieved in low carrier density crystals. In addition, both the band gap and reduced effective mass of carriers are determined. (C) 2010 American Institute of Physics. [doi:10.1063/1.3473778]