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

TL;DR

This study investigates how the bulk and surface transport properties of Bi2Se3 topological insulators depend on thickness, revealing key behaviors of carrier density, mobility, and quantum interference effects across a wide range of sample sizes.

Contribution

It provides a comprehensive analysis of thickness-dependent electronic properties and weak anti-localization effects in Bi2Se3, highlighting the interplay between surface and bulk states.

Findings

Carrier density decreases with thickness due to selenium vacancies.

Mobility increases with thickness and saturates at larger scales.

Weak anti-localization is dominated by a single 2D channel across various thicknesses.

Abstract

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 \mu m). 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.