Effect of Silver Doping on Transport Properties of Bi 2 Se 3 : Ag x Bi 2 Se 3 and Bi 2−x Ag x Se 3

Ag-doped Bi 2 Se 3 with the formula Ag x Bi 2 Se 3 and Bi 2−x Ag x Se 3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi 2 Se 3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.