Structural and electronic transport properties of Zn- and Ga-doped Bi2-xSbxTe3-ySey topological insulator single crystals.

A comprehensive study of structural and magnetotransport properties of pristine Bi2-xSbxTe3-ySey (BSTS) single crystals and doped with Zn (BSTS:Zn) and Ga (BSTS:Ga) are presented here. Magnetic field dependent Hall resistivities of the single crystals indicate that the holes are the majority carriers. The field dependent resistivity curves at different temperatures of the crystals display cusp-like characteristics at low magnetic fields, attributed to two-dimensional (2D) weak antilocalization (WAL) effect. The Hikami-Larkin-Nagaoka (HLN) equation fit to the low field WAL effects at various temperatures reveal a phase coherence length (lϕ) that decreases as temperature increases. The variation of lϕ with temperature follows T-0.41 power law for BSTS:Zn, suggesting that the dominant dephasing mechanism is a 2D electron-electron (e-e) interactions. For pristine BSTS and BSTS:Ga, lϕ(T) is described by considering a coexistence of 2D e-e and electron-phonon (e-p) interactions in the single crystals. The temperature variation of the longitudinal resistance in BSTS:Ga is described by three-dimensional (3D) Mott variable range hoping model. In contrast, the transport mechanisms of both pristine BSTS and BSTS:Zn are described by a combination of 2D WAL/EEI models and 3D WAL. .