Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide

TL;DR

This study demonstrates gate-voltage tuning of carrier density and weak anti-localization effects in Bi2Se3 thin films grown on SrTiO3, revealing surface state contributions and potential for topological insulator applications.

Contribution

It shows large tunability of carrier density in Bi2Se3 films via gating and links WAL behavior to surface states, advancing understanding of topological insulator surface phenomena.

Findings

Gate voltage effectively tunes carrier density in Bi2Se3 films.

Weak anti-localization shows minimal gate dependence except at very low electron densities.

Surface states likely contribute to WAL phenomena at large negative gate voltages.

Abstract

We report that Bi$_2$Se$_3$ thin films can be epitaxially grown on SrTiO$_{3}$ substrates, which allow for very large tunablity in carrier density with a back-gate. The observed low field magnetoconductivity due to weak anti-localization (WAL) has a very weak gate-voltage dependence unless the electron density is reduced to very low values. Such a transition in WAL is correlated with unusual changes in longitudinal and Hall resistivities. Our results suggest much suppressed bulk conductivity at large negative gate-voltages and a possible role of surface states in the WAL phenomena. This work may pave a way for realizing three-dimensional topological insulators at ambient conditions.