Structural and transport properties of iridium-doped Bi2Se3 topological insulator crystals

Iridium doped Bi2Se3 crystals have been prepared by self-flux method. Their crystalline, morphological, Raman spectra, and transport properties were investigated. The obtained crystals have typical topological insulator characteristics. Same layered structure was confirmed for all samples. The lattice parameter c first decreased and then increased with increasing Ir content. All samples showed two characteristic Raman peaks of Bi2Se3 with one of them blue-shifting as the Ir content increased. The magnetoresistance as well as the resistivity increased first and then decreased with increasing Ir content. The doping mechanism was considered that Ir atoms mainly occupied Bi sites when doped content was lower but they tended to intercalate into atomic layers and van der Waals gap at higher doping content.