Thickness-dependent bulk properties and weak anti-localization effect in topological insulator Bi2Se3

We show that a number of transport properties in topological insulator (TI) Bi2Se3 exhibit striking thickness-dependences over a range of up to five orders of thickness (3 nm - 170 μm). Volume carrier density decreased with thickness, presumably due to diffusion-limited formation of selenium vacancies. Mobility increased linearly with thickness in the thin film regime and saturated in the thick limit. The weak anti-localization effect was dominated by a single two-dimensional channel over two decades of thickness. The sublinear thickness-dependence of the phase coherence length suggests the presence of strong coupling between the surface and bulk states.

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